Pylint features
***************


Pylint global options and switches
==================================

Pylint provides global options and switches.


General options
---------------

ignore:
   Files or directories to be skipped. They should be base names, not
   paths.

   Default: "CVS"

ignore-patterns:
   Files or directories matching the regex patterns are skipped. The
   regex matches against base names, not paths.

ignore-paths:
   Add files or directories matching the regex patterns to the ignore-
   list. The regex matches against paths and can be in Posix or
   Windows format.

persistent:
   Pickle collected data for later comparisons.

   Default: "yes"

load-plugins:
   List of plugins (as comma separated values of python module names)
   to load, usually to register additional checkers.

fail-under:
   Specify a score threshold to be exceeded before program exits with
   error.

   Default: "10.0"

fail-on:
   Return non-zero exit code if any of these messages/categories are
   detected, even if score is above --fail-under value. Syntax same as
   enable. Messages specified are enabled, while categories only check
   already-enabled messages.

jobs:
   Use multiple processes to speed up Pylint. Specifying 0 will auto-
   detect the number of processors available to use.

   Default: "1"

unsafe-load-any-extension:
   Allow loading of arbitrary C extensions. Extensions are imported
   into the active Python interpreter and may run arbitrary code.

limit-inference-results:
   Control the amount of potential inferred values when inferring a
   single object. This can help the performance when dealing with
   large functions or complex, nested conditions.

   Default: "100"

extension-pkg-allow-list:
   A comma-separated list of package or module names from where C
   extensions may be loaded. Extensions are loading into the active
   Python interpreter and may run arbitrary code.

extension-pkg-whitelist:
   A comma-separated list of package or module names from where C
   extensions may be loaded. Extensions are loading into the active
   Python interpreter and may run arbitrary code. (This is an
   alternative name to extension-pkg-allow-list for backward
   compatibility.)

suggestion-mode:
   When enabled, pylint would attempt to guess common misconfiguration
   and emit user-friendly hints instead of false-positive error
   messages.

   Default: "yes"

exit-zero:
   Always return a 0 (non-error) status code, even if lint errors are
   found. This is primarily useful in continuous integration scripts.

from-stdin:
   Interpret the stdin as a python script, whose filename needs to be
   passed as the module_or_package argument.

py-version:
   Minimum Python version to use for version dependent checks. Will
   default to the version used to run pylint.


Messages control options
------------------------

confidence:
   Only show warnings with the listed confidence levels. Leave empty
   to show all. Valid levels: HIGH, INFERENCE, INFERENCE_FAILURE,
   UNDEFINED.

enable:
   Enable the message, report, category or checker with the given
   id(s). You can either give multiple identifier separated by comma
   (,) or put this option multiple time (only on the command line, not
   in the configuration file where it should appear only once). See
   also the "--disable" option for examples.

disable:
   Disable the message, report, category or checker with the given
   id(s). You can either give multiple identifiers separated by comma
   (,) or put this option multiple times (only on the command line,
   not in the configuration file where it should appear only once).
   You can also use "--disable=all" to disable everything first and
   then reenable specific checks. For example, if you want to run only
   the similarities checker, you can use "--disable=all
   --enable=similarities". If you want to run only the classes
   checker, but have no Warning level messages displayed, use "--
   disable=all --enable=classes --disable=W".


Reports options
---------------

output-format:
   Set the output format. Available formats are text, parseable,
   colorized, json and msvs (visual studio). You can also give a
   reporter class, e.g. mypackage.mymodule.MyReporterClass.

   Default: "text"

reports:
   Tells whether to display a full report or only the messages.

evaluation:
   Python expression which should return a score less than or equal to
   10. You have access to the variables 'error', 'warning',
   'refactor', and 'convention' which contain the number of messages
   in each category, as well as 'statement' which is the total number
   of statements analyzed. This score is used by the global evaluation
   report (RP0004).

   Default: "10.0 - ((float(5 * error + warning + refactor +
   convention) / statement) * 10)"

score:
   Activate the evaluation score.

   Default: "yes"

msg-template:
   Template used to display messages. This is a python new-style
   format string used to format the message information. See doc for
   all details.


Pylint checkers' options and switches
=====================================

Pylint checkers can provide three set of features:

* options that control their execution,

* messages that they can raise,

* reports that they can generate.

Below is a list of all checkers and their features.


Async checker
-------------

Verbatim name of the checker is "async".


Async checker Messages
~~~~~~~~~~~~~~~~~~~~~~

not-async-context-manager (E1701):
   *Async context manager '%s' doesn't implement __aenter__ and
   __aexit__.* Used when an async context manager is used with an
   object that does not implement the async context management
   protocol. This message can't be emitted when using Python < 3.5.

yield-inside-async-function (E1700):
   *Yield inside async function* Used when an *yield* or *yield from*
   statement is found inside an async function. This message can't be
   emitted when using Python < 3.5.


Basic checker
-------------

Verbatim name of the checker is "basic".


Basic checker Options
~~~~~~~~~~~~~~~~~~~~~

good-names:
   Good variable names which should always be accepted, separated by a
   comma.

   Default: "i,j,k,ex,Run,_"

good-names-rgxs:
   Good variable names regexes, separated by a comma. If names match
   any regex, they will always be accepted

bad-names:
   Bad variable names which should always be refused, separated by a
   comma.

   Default: "foo,bar,baz,toto,tutu,tata"

bad-names-rgxs:
   Bad variable names regexes, separated by a comma. If names match
   any regex, they will always be refused

name-group:
   Colon-delimited sets of names that determine each other's naming
   style when the name regexes allow several styles.

include-naming-hint:
   Include a hint for the correct naming format with invalid-name.

property-classes:
   List of decorators that produce properties, such as
   abc.abstractproperty. Add to this list to register other decorators
   that produce valid properties. These decorators are taken in
   consideration only for invalid-name.

   Default: "abc.abstractproperty"

argument-naming-style:
   Naming style matching correct argument names.

   Default: "snake_case"

argument-rgx:
   Regular expression matching correct argument names. Overrides
   argument- naming-style.

attr-naming-style:
   Naming style matching correct attribute names.

   Default: "snake_case"

attr-rgx:
   Regular expression matching correct attribute names. Overrides
   attr-naming- style.

class-naming-style:
   Naming style matching correct class names.

   Default: "PascalCase"

class-rgx:
   Regular expression matching correct class names. Overrides class-
   naming- style.

class-attribute-naming-style:
   Naming style matching correct class attribute names.

   Default: "any"

class-attribute-rgx:
   Regular expression matching correct class attribute names.
   Overrides class- attribute-naming-style.

class-const-naming-style:
   Naming style matching correct class constant names.

   Default: "UPPER_CASE"

class-const-rgx:
   Regular expression matching correct class constant names. Overrides
   class- const-naming-style.

const-naming-style:
   Naming style matching correct constant names.

   Default: "UPPER_CASE"

const-rgx:
   Regular expression matching correct constant names. Overrides
   const-naming- style.

function-naming-style:
   Naming style matching correct function names.

   Default: "snake_case"

function-rgx:
   Regular expression matching correct function names. Overrides
   function- naming-style.

inlinevar-naming-style:
   Naming style matching correct inline iteration names.

   Default: "any"

inlinevar-rgx:
   Regular expression matching correct inline iteration names.
   Overrides inlinevar-naming-style.

method-naming-style:
   Naming style matching correct method names.

   Default: "snake_case"

method-rgx:
   Regular expression matching correct method names. Overrides method-
   naming- style.

module-naming-style:
   Naming style matching correct module names.

   Default: "snake_case"

module-rgx:
   Regular expression matching correct module names. Overrides module-
   naming- style.

variable-naming-style:
   Naming style matching correct variable names.

   Default: "snake_case"

variable-rgx:
   Regular expression matching correct variable names. Overrides
   variable- naming-style.

no-docstring-rgx:
   Regular expression which should only match function or class names
   that do not require a docstring.

   Default: "^_"

docstring-min-length:
   Minimum line length for functions/classes that require docstrings,
   shorter ones are exempt.

   Default: "-1"


Basic checker Messages
~~~~~~~~~~~~~~~~~~~~~~

not-in-loop (E0103):
   *%r not properly in loop* Used when break or continue keywords are
   used outside a loop.

function-redefined (E0102):
   *%s already defined line %s* Used when a function / class / method
   is redefined.

continue-in-finally (E0116):
   *'continue' not supported inside 'finally' clause* Emitted when the
   *continue* keyword is found inside a finally clause, which is a
   SyntaxError. This message can't be emitted when using Python >=
   3.8.

abstract-class-instantiated (E0110):
   *Abstract class %r with abstract methods instantiated* Used when an
   abstract class with *abc.ABCMeta* as metaclass has abstract methods
   and is instantiated.

star-needs-assignment-target (E0114):
   *Can use starred expression only in assignment target* Emitted when
   a star expression is not used in an assignment target.

duplicate-argument-name (E0108):
   *Duplicate argument name %s in function definition* Duplicate
   argument names in function definitions are syntax errors.

return-in-init (E0101):
   *Explicit return in __init__* Used when the special class method
   __init__ has an explicit return value.

too-many-star-expressions (E0112):
   *More than one starred expression in assignment* Emitted when there
   are more than one starred expressions (**x*) in an assignment. This
   is a SyntaxError.

nonlocal-and-global (E0115):
   *Name %r is nonlocal and global* Emitted when a name is both
   nonlocal and global.

used-prior-global-declaration (E0118):
   *Name %r is used prior to global declaration* Emitted when a name
   is used prior a global declaration, which results in an error since
   Python 3.6. This message can't be emitted when using Python < 3.6.

return-outside-function (E0104):
   *Return outside function* Used when a "return" statement is found
   outside a function or method.

return-arg-in-generator (E0106):
   *Return with argument inside generator* Used when a "return"
   statement with an argument is found outside in a generator function
   or method (e.g. with some "yield" statements). This message can't
   be emitted when using Python >= 3.3.

invalid-star-assignment-target (E0113):
   *Starred assignment target must be in a list or tuple* Emitted when
   a star expression is used as a starred assignment target.

bad-reversed-sequence (E0111):
   *The first reversed() argument is not a sequence* Used when the
   first argument to reversed() builtin isn't a sequence (does not
   implement __reversed__, nor __getitem__ and __len__

nonexistent-operator (E0107):
   *Use of the non-existent %s operator* Used when you attempt to use
   the C-style pre-increment or pre-decrement operator -- and ++,
   which doesn't exist in Python.

yield-outside-function (E0105):
   *Yield outside function* Used when a "yield" statement is found
   outside a function or method.

init-is-generator (E0100):
   *__init__ method is a generator* Used when the special class method
   __init__ is turned into a generator by a yield in its body.

misplaced-format-function (E0119):
   *format function is not called on str* Emitted when format function
   is not called on str object. e.g doing print("value:
   {}").format(123) instead of print("value: {}".format(123)). This
   might not be what the user intended to do.

nonlocal-without-binding (E0117):
   *nonlocal name %s found without binding* Emitted when a nonlocal
   variable does not have an attached name somewhere in the parent
   scopes

lost-exception (W0150):
   *%s statement in finally block may swallow exception* Used when a
   break or a return statement is found inside the finally clause of a
   try...finally block: the exceptions raised in the try clause will
   be silently swallowed instead of being re-raised.

assert-on-tuple (W0199):
   *Assert called on a 2-item-tuple. Did you mean 'assert x,y'?* A
   call of assert on a tuple will always evaluate to true if the tuple
   is not empty, and will always evaluate to false if it is.

assert-on-string-literal (W0129):
   *Assert statement has a string literal as its first argument. The
   assert will %s fail.* Used when an assert statement has a string
   literal as its first argument, which will cause the assert to
   always pass.

self-assigning-variable (W0127):
   *Assigning the same variable %r to itself* Emitted when we detect
   that a variable is assigned to itself

comparison-with-callable (W0143):
   *Comparing against a callable, did you omit the parenthesis?* This
   message is emitted when pylint detects that a comparison with a
   callable was made, which might suggest that some parenthesis were
   omitted, resulting in potential unwanted behaviour.

nan-comparison (W0177):
   *Comparison %s should be %s* Used when an expression is compared to
   NaNvalues like numpy.NaN and float('nan')

dangerous-default-value (W0102):
   *Dangerous default value %s as argument* Used when a mutable value
   as list or dictionary is detected in a default value for an
   argument.

duplicate-key (W0109):
   *Duplicate key %r in dictionary* Used when a dictionary expression
   binds the same key multiple times.

useless-else-on-loop (W0120):
   *Else clause on loop without a break statement* Loops should only
   have an else clause if they can exit early with a break statement,
   otherwise the statements under else should be on the same scope as
   the loop itself.

expression-not-assigned (W0106):
   *Expression "%s" is assigned to nothing* Used when an expression
   that is not a function call is assigned to nothing. Probably
   something else was intended.

confusing-with-statement (W0124):
   *Following "as" with another context manager looks like a tuple.*
   Emitted when a *with* statement component returns multiple values
   and uses name binding with *as* only for a part of those values, as
   in with ctx() as a, b. This can be misleading, since it's not clear
   if the context manager returns a tuple or if the node without a
   name binding is another context manager.

unnecessary-lambda (W0108):
   *Lambda may not be necessary* Used when the body of a lambda
   expression is a function call on the same argument list as the
   lambda itself; such lambda expressions are in all but a few cases
   replaceable with the function being called in the body of the
   lambda.

assign-to-new-keyword (W0111):
   *Name %s will become a keyword in Python %s* Used when assignment
   will become invalid in future Python release due to introducing new
   keyword.

redeclared-assigned-name (W0128):
   *Redeclared variable %r in assignment* Emitted when we detect that
   a variable was redeclared in the same assignment.

pointless-statement (W0104):
   *Statement seems to have no effect* Used when a statement doesn't
   have (or at least seems to) any effect.

pointless-string-statement (W0105):
   *String statement has no effect* Used when a string is used as a
   statement (which of course has no effect). This is a particular
   case of W0104 with its own message so you can easily disable it if
   you're using those strings as documentation, instead of comments.

unnecessary-pass (W0107):
   *Unnecessary pass statement* Used when a "pass" statement that can
   be avoided is encountered.

unreachable (W0101):
   *Unreachable code* Used when there is some code behind a "return"
   or "raise" statement, which will never be accessed.

eval-used (W0123):
   *Use of eval* Used when you use the "eval" function, to discourage
   its usage. Consider using *ast.literal_eval* for safely evaluating
   strings containing Python expressions from untrusted sources.

exec-used (W0122):
   *Use of exec* Used when you use the "exec" statement (function for
   Python 3), to discourage its usage. That doesn't mean you cannot
   use it !

using-constant-test (W0125):
   *Using a conditional statement with a constant value* Emitted when
   a conditional statement (If or ternary if) uses a constant value
   for its test. This might not be what the user intended to do.

missing-parentheses-for-call-in-test (W0126):
   *Using a conditional statement with potentially wrong function or
   method call due to missing parentheses* Emitted when a conditional
   statement (If or ternary if) seems to wrongly call a function due
   to missing parentheses

literal-comparison (R0123):
   *Comparison to literal* Used when comparing an object to a literal,
   which is usually what you do not want to do, since you can compare
   to a different literal than what was expected altogether.

comparison-with-itself (R0124):
   *Redundant comparison - %s* Used when something is compared against
   itself.

non-ascii-name (C0144):
   *%s name "%s" contains a non-ASCII unicode character* Used when the
   name contains at least one non-ASCII unicode character.

invalid-name (C0103):
   *%s name "%s" doesn't conform to %s* Used when the name doesn't
   conform to naming rules associated to its type (constant, variable,
   class...).

singleton-comparison (C0121):
   *Comparison %s should be %s* Used when an expression is compared to
   singleton values like True, False or None.

disallowed-name (C0104):
   *Disallowed name "%s"* Used when the name matches bad-names or bad-
   names-rgxs- (unauthorized names).

empty-docstring (C0112):
   *Empty %s docstring* Used when a module, function, class or method
   has an empty docstring (it would be too easy ;).

missing-class-docstring (C0115):
   *Missing class docstring* Used when a class has no docstring.Even
   an empty class must have a docstring.

missing-function-docstring (C0116):
   *Missing function or method docstring* Used when a function or
   method has no docstring.Some special methods like __init__ do not
   require a docstring.

missing-module-docstring (C0114):
   *Missing module docstring* Used when a module has no
   docstring.Empty modules do not require a docstring.

unidiomatic-typecheck (C0123):
   *Use isinstance() rather than type() for a typecheck.* The
   idiomatic way to perform an explicit typecheck in Python is to use
   isinstance(x, Y) rather than type(x) == Y, type(x) is Y. Though
   there are unusual situations where these give different results.


Basic checker Reports
~~~~~~~~~~~~~~~~~~~~~

RP0101:
   Statistics by type


Classes checker
---------------

Verbatim name of the checker is "classes".


Classes checker Options
~~~~~~~~~~~~~~~~~~~~~~~

defining-attr-methods:
   List of method names used to declare (i.e. assign) instance
   attributes.

   Default: "__init__,__new__,setUp,__post_init__"

valid-classmethod-first-arg:
   List of valid names for the first argument in a class method.

   Default: "cls"

valid-metaclass-classmethod-first-arg:
   List of valid names for the first argument in a metaclass class
   method.

   Default: "cls"

exclude-protected:
   List of member names, which should be excluded from the protected
   access warning.

   Default: "_asdict,_fields,_replace,_source,_make"

check-protected-access-in-special-methods:
   Warn about protected attribute access inside special methods


Classes checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~

access-member-before-definition (E0203):
   *Access to member %r before its definition line %s* Used when an
   instance member is accessed before it's actually assigned.

method-hidden (E0202):
   *An attribute defined in %s line %s hides this method* Used when a
   class defines a method which is hidden by an instance attribute
   from an ancestor class or set by some client code.

assigning-non-slot (E0237):
   *Assigning to attribute %r not defined in class slots* Used when
   assigning to an attribute not defined in the class slots.

duplicate-bases (E0241):
   *Duplicate bases for class %r* Used when a class has duplicate
   bases.

inconsistent-mro (E0240):
   *Inconsistent method resolution order for class %r* Used when a
   class has an inconsistent method resolution order.

inherit-non-class (E0239):
   *Inheriting %r, which is not a class.* Used when a class inherits
   from something which is not a class.

invalid-class-object (E0243):
   *Invalid __class__ object* Used when an invalid object is assigned
   to a __class__ property. Only a class is permitted.

invalid-slots (E0238):
   *Invalid __slots__ object* Used when an invalid __slots__ is found
   in class. Only a string, an iterable or a sequence is permitted.

invalid-slots-object (E0236):
   *Invalid object %r in __slots__, must contain only non empty
   strings* Used when an invalid (non-string) object occurs in
   __slots__.

no-method-argument (E0211):
   *Method has no argument* Used when a method which should have the
   bound instance as first argument has no argument defined.

no-self-argument (E0213):
   *Method should have "self" as first argument* Used when a method
   has an attribute different the "self" as first argument. This is
   considered as an error since this is a so common convention that
   you shouldn't break it!

unexpected-special-method-signature (E0302):
   *The special method %r expects %s param(s), %d %s given* Emitted
   when a special method was defined with an invalid number of
   parameters. If it has too few or too many, it might not work at
   all.

class-variable-slots-conflict (E0242):
   *Value %r in slots conflicts with class variable* Used when a value
   in __slots__ conflicts with a class variable, property or method.

invalid-bool-returned (E0304):
   *__bool__ does not return bool* Used when a __bool__ method returns
   something which is not a bool

invalid-bytes-returned (E0308):
   *__bytes__ does not return bytes* Used when a __bytes__ method
   returns something which is not bytes

invalid-format-returned (E0311):
   *__format__ does not return str* Used when a __format__ method
   returns something which is not a string

invalid-getnewargs-returned (E0312):
   *__getnewargs__ does not return a tuple* Used when a __getnewargs__
   method returns something which is not a tuple

invalid-getnewargs-ex-returned (E0313):
   *__getnewargs_ex__ does not return a tuple containing (tuple,
   dict)* Used when a __getnewargs_ex__ method returns something which
   is not of the form tuple(tuple, dict)

invalid-hash-returned (E0309):
   *__hash__ does not return int* Used when a __hash__ method returns
   something which is not an integer

invalid-index-returned (E0305):
   *__index__ does not return int* Used when an __index__ method
   returns something which is not an integer

non-iterator-returned (E0301):
   *__iter__ returns non-iterator* Used when an __iter__ method
   returns something which is not an iterable (i.e. has no *__next__*
   method)

invalid-length-returned (E0303):
   *__len__ does not return non-negative integer* Used when a __len__
   method returns something which is not a non-negative integer

invalid-length-hint-returned (E0310):
   *__length_hint__ does not return non-negative integer* Used when a
   __length_hint__ method returns something which is not a non-
   negative integer

invalid-repr-returned (E0306):
   *__repr__ does not return str* Used when a __repr__ method returns
   something which is not a string

invalid-str-returned (E0307):
   *__str__ does not return str* Used when a __str__ method returns
   something which is not a string

arguments-differ (W0221):
   *%s %s %r method* Used when a method has a different number of
   arguments than in the implemented interface or in an overridden
   method.

arguments-renamed (W0237):
   *%s %s %r method* Used when a method parameter has a different name
   than in the implemented interface or in an overridden method.

protected-access (W0212):
   *Access to a protected member %s of a client class* Used when a
   protected member (i.e. class member with a name beginning with an
   underscore) is access outside the class or a descendant of the
   class where it's defined.

attribute-defined-outside-init (W0201):
   *Attribute %r defined outside __init__* Used when an instance
   attribute is defined outside the __init__ method.

subclassed-final-class (W0240):
   *Class %r is a subclass of a class decorated with typing.final: %r*
   Used when a class decorated with typing.final has been subclassed.

no-init (W0232):
   *Class has no __init__ method* Used when a class has no __init__
   method, neither its parent classes.

abstract-method (W0223):
   *Method %r is abstract in class %r but is not overridden* Used when
   an abstract method (i.e. raise NotImplementedError) is not
   overridden in concrete class.

overridden-final-method (W0239):
   *Method %r overrides a method decorated with typing.final which is
   defined in class %r* Used when a method decorated with typing.final
   has been overridden.

invalid-overridden-method (W0236):
   *Method %r was expected to be %r, found it instead as %r* Used when
   we detect that a method was overridden in a way that does not match
   its base class which could result in potential bugs at runtime.

signature-differs (W0222):
   *Signature differs from %s %r method* Used when a method signature
   is different than in the implemented interface or in an overridden
   method.

bad-staticmethod-argument (W0211):
   *Static method with %r as first argument* Used when a static method
   has "self" or a value specified in valid- classmethod-first-arg
   option or valid-metaclass-classmethod-first-arg option as first
   argument.

unused-private-member (W0238):
   *Unused private member `%s.%s`* Emitted when a private member of a
   class is defined but not used.

useless-super-delegation (W0235):
   *Useless super delegation in method %r* Used whenever we can detect
   that an overridden method is useless, relying on super() delegation
   to do the same thing as another method from the MRO.

non-parent-init-called (W0233):
   *__init__ method from a non direct base class %r is called* Used
   when an __init__ method is called on a class which is not in the
   direct ancestors for the analysed class.

super-init-not-called (W0231):
   *__init__ method from base class %r is not called* Used when an
   ancestor class method has an __init__ method which is not called by
   a derived class.

property-with-parameters (R0206):
   *Cannot have defined parameters for properties* Used when we detect
   that a property also has parameters, which are useless, given that
   properties cannot be called with additional arguments.

useless-object-inheritance (R0205):
   *Class %r inherits from object, can be safely removed from bases in
   python3* Used when a class inherit from object, which under python3
   is implicit, hence can be safely removed from bases.

no-classmethod-decorator (R0202):
   *Consider using a decorator instead of calling classmethod* Used
   when a class method is defined without using the decorator syntax.

no-staticmethod-decorator (R0203):
   *Consider using a decorator instead of calling staticmethod* Used
   when a static method is defined without using the decorator syntax.

no-self-use (R0201):
   *Method could be a function* Used when a method doesn't use its
   bound instance, and so could be written as a function.

single-string-used-for-slots (C0205):
   *Class __slots__ should be a non-string iterable* Used when a class
   __slots__ is a simple string, rather than an iterable.

bad-classmethod-argument (C0202):
   *Class method %s should have %s as first argument* Used when a
   class method has a first argument named differently than the value
   specified in valid-classmethod-first-arg option (default to "cls"),
   recommended to easily differentiate them from regular instance
   methods.

bad-mcs-classmethod-argument (C0204):
   *Metaclass class method %s should have %s as first argument* Used
   when a metaclass class method has a first argument named
   differently than the value specified in valid-metaclass-
   classmethod-first-arg option (default to "mcs"), recommended to
   easily differentiate them from regular instance methods.

bad-mcs-method-argument (C0203):
   *Metaclass method %s should have %s as first argument* Used when a
   metaclass method has a first argument named differently than the
   value specified in valid-classmethod-first-arg option (default to
   "cls"), recommended to easily differentiate them from regular
   instance methods.

method-check-failed (F0202):
   *Unable to check methods signature (%s / %s)* Used when Pylint has
   been unable to check methods signature compatibility for an
   unexpected reason. Please report this kind if you don't make sense
   of it.


Design checker
--------------

Verbatim name of the checker is "design".


Design checker Options
~~~~~~~~~~~~~~~~~~~~~~

max-args:
   Maximum number of arguments for function / method.

   Default: "5"

max-locals:
   Maximum number of locals for function / method body.

   Default: "15"

max-returns:
   Maximum number of return / yield for function / method body.

   Default: "6"

max-branches:
   Maximum number of branch for function / method body.

   Default: "12"

max-statements:
   Maximum number of statements in function / method body.

   Default: "50"

max-parents:
   Maximum number of parents for a class (see R0901).

   Default: "7"

ignored-parents:
   List of qualified class names to ignore when counting class parents
   (see R0901)

max-attributes:
   Maximum number of attributes for a class (see R0902).

   Default: "7"

min-public-methods:
   Minimum number of public methods for a class (see R0903).

   Default: "2"

max-public-methods:
   Maximum number of public methods for a class (see R0904).

   Default: "20"

max-bool-expr:
   Maximum number of boolean expressions in an if statement (see
   R0916).

   Default: "5"

exclude-too-few-public-methods:
   List of regular expressions of class ancestor names to ignore when
   counting public methods (see R0903)


Design checker Messages
~~~~~~~~~~~~~~~~~~~~~~~

too-few-public-methods (R0903):
   *Too few public methods (%s/%s)* Used when class has too few public
   methods, so be sure it's really worth it.

too-many-ancestors (R0901):
   *Too many ancestors (%s/%s)* Used when class has too many parent
   classes, try to reduce this to get a simpler (and so easier to use)
   class.

too-many-arguments (R0913):
   *Too many arguments (%s/%s)* Used when a function or method takes
   too many arguments.

too-many-boolean-expressions (R0916):
   *Too many boolean expressions in if statement (%s/%s)* Used when an
   if statement contains too many boolean expressions.

too-many-branches (R0912):
   *Too many branches (%s/%s)* Used when a function or method has too
   many branches, making it hard to follow.

too-many-instance-attributes (R0902):
   *Too many instance attributes (%s/%s)* Used when class has too many
   instance attributes, try to reduce this to get a simpler (and so
   easier to use) class.

too-many-locals (R0914):
   *Too many local variables (%s/%s)* Used when a function or method
   has too many local variables.

too-many-public-methods (R0904):
   *Too many public methods (%s/%s)* Used when class has too many
   public methods, try to reduce this to get a simpler (and so easier
   to use) class.

too-many-return-statements (R0911):
   *Too many return statements (%s/%s)* Used when a function or method
   has too many return statement, making it hard to follow.

too-many-statements (R0915):
   *Too many statements (%s/%s)* Used when a function or method has
   too many statements. You should then split it in smaller functions
   / methods.


Exceptions checker
------------------

Verbatim name of the checker is "exceptions".


Exceptions checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~~

overgeneral-exceptions:
   Exceptions that will emit a warning when being caught. Defaults to
   "BaseException, Exception".

   Default: "BaseException,Exception"


Exceptions checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~

bad-except-order (E0701):
   *Bad except clauses order (%s)* Used when except clauses are not in
   the correct order (from the more specific to the more generic). If
   you don't fix the order, some exceptions may not be caught by the
   most specific handler.

catching-non-exception (E0712):
   *Catching an exception which doesn't inherit from Exception: %s*
   Used when a class which doesn't inherit from Exception is used as
   an exception in an except clause.

bad-exception-context (E0703):
   *Exception context set to something which is not an exception, nor
   None* Used when using the syntax "raise ... from ...", where the
   exception context is not an exception, nor None.

notimplemented-raised (E0711):
   *NotImplemented raised - should raise NotImplementedError* Used
   when NotImplemented is raised instead of NotImplementedError

raising-bad-type (E0702):
   *Raising %s while only classes or instances are allowed* Used when
   something which is neither a class, an instance or a string is
   raised (i.e. a *TypeError* will be raised).

raising-non-exception (E0710):
   *Raising a new style class which doesn't inherit from
   BaseException* Used when a new style class which doesn't inherit
   from BaseException is raised.

misplaced-bare-raise (E0704):
   *The raise statement is not inside an except clause* Used when a
   bare raise is not used inside an except clause. This generates an
   error, since there are no active exceptions to be reraised. An
   exception to this rule is represented by a bare raise inside a
   finally clause, which might work, as long as an exception is raised
   inside the try block, but it is nevertheless a code smell that must
   not be relied upon.

duplicate-except (W0705):
   *Catching previously caught exception type %s* Used when an except
   catches a type that was already caught by a previous handler.

broad-except (W0703):
   *Catching too general exception %s* Used when an except catches a
   too general exception, possibly burying unrelated errors.

raise-missing-from (W0707):
   *Consider explicitly re-raising using the 'from' keyword* Python
   3's exception chaining means it shows the traceback of the current
   exception, but also the original exception. Not using *raise from*
   makes the traceback inaccurate, because the message implies there
   is a bug in the exception-handling code itself, which is a separate
   situation than wrapping an exception.

raising-format-tuple (W0715):
   *Exception arguments suggest string formatting might be intended*
   Used when passing multiple arguments to an exception constructor,
   the first of them a string literal containing what appears to be
   placeholders intended for formatting

binary-op-exception (W0711):
   *Exception to catch is the result of a binary "%s" operation* Used
   when the exception to catch is of the form "except A or B:". If
   intending to catch multiple, rewrite as "except (A, B):"

wrong-exception-operation (W0716):
   *Invalid exception operation. %s* Used when an operation is done
   against an exception, but the operation is not valid for the
   exception in question. Usually emitted when having binary
   operations between exceptions in except handlers.

bare-except (W0702):
   *No exception type(s) specified* Used when an except clause doesn't
   specify exceptions type to catch.

try-except-raise (W0706):
   *The except handler raises immediately* Used when an except handler
   uses raise as its first or only operator. This is useless because
   it raises back the exception immediately. Remove the raise operator
   or the entire try-except-raise block!


Format checker
--------------

Verbatim name of the checker is "format".


Format checker Options
~~~~~~~~~~~~~~~~~~~~~~

max-line-length:
   Maximum number of characters on a single line.

   Default: "100"

ignore-long-lines:
   Regexp for a line that is allowed to be longer than the limit.

   Default: "^\s*(# )?<?https?://\S+>?$"

single-line-if-stmt:
   Allow the body of an if to be on the same line as the test if there
   is no else.

single-line-class-stmt:
   Allow the body of a class to be on the same line as the declaration
   if body contains single statement.

max-module-lines:
   Maximum number of lines in a module.

   Default: "1000"

indent-string:
   String used as indentation unit. This is usually "    " (4 spaces)
   or "t" (1 tab).

   Default: "'    '"

indent-after-paren:
   Number of spaces of indent required inside a hanging or continued
   line.

   Default: "4"

expected-line-ending-format:
   Expected format of line ending, e.g. empty (any line ending), LF or
   CRLF.


Format checker Messages
~~~~~~~~~~~~~~~~~~~~~~~

bad-indentation (W0311):
   *Bad indentation. Found %s %s, expected %s* Used when an unexpected
   number of indentation's tabulations or spaces has been found.

unnecessary-semicolon (W0301):
   *Unnecessary semicolon* Used when a statement is ended by a semi-
   colon (";"), which isn't necessary (that's python, not C ;).

missing-final-newline (C0304):
   *Final newline missing* Used when the last line in a file is
   missing a newline.

line-too-long (C0301):
   *Line too long (%s/%s)* Used when a line is longer than a given
   number of characters.

mixed-line-endings (C0327):
   *Mixed line endings LF and CRLF* Used when there are mixed (LF and
   CRLF) newline signs in a file.

multiple-statements (C0321):
   *More than one statement on a single line* Used when more than on
   statement are found on the same line.

too-many-lines (C0302):
   *Too many lines in module (%s/%s)* Used when a module has too many
   lines, reducing its readability.

trailing-newlines (C0305):
   *Trailing newlines* Used when there are trailing blank lines in a
   file.

trailing-whitespace (C0303):
   *Trailing whitespace* Used when there is whitespace between the end
   of a line and the newline.

unexpected-line-ending-format (C0328):
   *Unexpected line ending format. There is '%s' while it should be
   '%s'.* Used when there is different newline than expected.

superfluous-parens (C0325):
   *Unnecessary parens after %r keyword* Used when a single item in
   parentheses follows an if, for, or other keyword.


Imports checker
---------------

Verbatim name of the checker is "imports".


Imports checker Options
~~~~~~~~~~~~~~~~~~~~~~~

deprecated-modules:
   Deprecated modules which should not be used, separated by a comma.

preferred-modules:
   Couples of modules and preferred modules, separated by a comma.

import-graph:
   Output a graph (.gv or any supported image format) of all (i.e.
   internal and external) dependencies to the given file (report
   RP0402 must not be disabled).

ext-import-graph:
   Output a graph (.gv or any supported image format) of external
   dependencies to the given file (report RP0402 must not be
   disabled).

int-import-graph:
   Output a graph (.gv or any supported image format) of internal
   dependencies to the given file (report RP0402 must not be
   disabled).

known-standard-library:
   Force import order to recognize a module as part of the standard
   compatibility libraries.

known-third-party:
   Force import order to recognize a module as part of a third party
   library.

   Default: "enchant"

allow-any-import-level:
   List of modules that can be imported at any level, not just the top
   level one.

analyse-fallback-blocks:
   Analyse import fallback blocks. This can be used to support both
   Python 2 and 3 compatible code, which means that the block might
   have code that exists only in one or another interpreter, leading
   to false positives when analysed.

allow-wildcard-with-all:
   Allow wildcard imports from modules that define __all__.


Imports checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~

relative-beyond-top-level (E0402):
   *Attempted relative import beyond top-level package* Used when a
   relative import tries to access too many levels in the current
   package.

import-error (E0401):
   *Unable to import %s* Used when pylint has been unable to import a
   module.

import-self (W0406):
   *Module import itself* Used when a module is importing itself.

preferred-module (W0407):
   *Prefer importing %r instead of %r* Used when a module imported has
   a preferred replacement module.

reimported (W0404):
   *Reimport %r (imported line %s)* Used when a module is reimported
   multiple times.

deprecated-module (W0402):
   *Uses of a deprecated module %r* Used a module marked as deprecated
   is imported.

wildcard-import (W0401):
   *Wildcard import %s* Used when *from module import ** is detected.

misplaced-future (W0410):
   *__future__ import is not the first non docstring statement* Python
   2.5 and greater require __future__ import to be the first non
   docstring statement in the module.

cyclic-import (R0401):
   *Cyclic import (%s)* Used when a cyclic import between two or more
   modules is detected.

consider-using-from-import (R0402):
   *Use 'from %s import %s' instead* Emitted when a submodule of a
   package is imported and aliased with the same name. E.g., instead
   of "import concurrent.futures as futures" use "from concurrent
   import futures"

wrong-import-order (C0411):
   *%s should be placed before %s* Used when PEP8 import order is not
   respected (standard imports first, then third-party libraries, then
   local imports)

wrong-import-position (C0413):
   *Import "%s" should be placed at the top of the module* Used when
   code and imports are mixed

useless-import-alias (C0414):
   *Import alias does not rename original package* Used when an import
   alias is same as original package.e.g using import numpy as numpy
   instead of import numpy as np

import-outside-toplevel (C0415):
   *Import outside toplevel (%s)* Used when an import statement is
   used anywhere other than the module toplevel. Move this import to
   the top of the file.

ungrouped-imports (C0412):
   *Imports from package %s are not grouped* Used when imports are not
   grouped by packages

multiple-imports (C0410):
   *Multiple imports on one line (%s)* Used when import statement
   importing multiple modules is detected.


Imports checker Reports
~~~~~~~~~~~~~~~~~~~~~~~

RP0401:
   External dependencies

RP0402:
   Modules dependencies graph


Logging checker
---------------

Verbatim name of the checker is "logging".


Logging checker Options
~~~~~~~~~~~~~~~~~~~~~~~

logging-modules:
   Logging modules to check that the string format arguments are in
   logging function parameter format.

   Default: "logging"

logging-format-style:
   The type of string formatting that logging methods do. *old* means
   using % formatting, *new* is for *{}* formatting.

   Default: "old"


Logging checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~

logging-format-truncated (E1201):
   *Logging format string ends in middle of conversion specifier* Used
   when a logging statement format string terminates before the end of
   a conversion specifier.

logging-too-few-args (E1206):
   *Not enough arguments for logging format string* Used when a
   logging format string is given too few arguments.

logging-too-many-args (E1205):
   *Too many arguments for logging format string* Used when a logging
   format string is given too many arguments.

logging-unsupported-format (E1200):
   *Unsupported logging format character %r (%#02x) at index %d* Used
   when an unsupported format character is used in a logging statement
   format string.

logging-format-interpolation (W1202):
   *Use %s formatting in logging functions* Used when a logging
   statement has a call form of "logging.<logging
   method>(format_string.format(format_args...))". Use another type of
   string formatting instead. You can use % formatting but leave
   interpolation to the logging function by passing the parameters as
   arguments. If logging-fstring- interpolation is disabled then you
   can use fstring formatting. If logging- not-lazy is disabled then
   you can use % formatting as normal.

logging-fstring-interpolation (W1203):
   *Use %s formatting in logging functions* Used when a logging
   statement has a call form of "logging.<logging method>(f"...")".Use
   another type of string formatting instead. You can use % formatting
   but leave interpolation to the logging function by passing the
   parameters as arguments. If logging-format-interpolation is
   disabled then you can use str.format. If logging-not-lazy is
   disabled then you can use % formatting as normal.

logging-not-lazy (W1201):
   *Use %s formatting in logging functions* Used when a logging
   statement has a call form of "logging.<logging
   method>(format_string % (format_args...))". Use another type of
   string formatting instead. You can use % formatting but leave
   interpolation to the logging function by passing the parameters as
   arguments. If logging-fstring- interpolation is disabled then you
   can use fstring formatting. If logging- format-interpolation is
   disabled then you can use str.format.


Metrics checker
---------------

Verbatim name of the checker is "metrics".


Metrics checker Reports
~~~~~~~~~~~~~~~~~~~~~~~

RP0701:
   Raw metrics


Miscellaneous checker
---------------------

Verbatim name of the checker is "miscellaneous".


Miscellaneous checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

notes:
   List of note tags to take in consideration, separated by a comma.

   Default: "FIXME,XXX,TODO"

notes-rgx:
   Regular expression of note tags to take in consideration.


Miscellaneous checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

fixme (W0511):
   Used when a warning note as FIXME or XXX is detected.

use-symbolic-message-instead (I0023):
   Used when a message is enabled or disabled by id.


Newstyle checker
----------------

Verbatim name of the checker is "newstyle".


Newstyle checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~

bad-super-call (E1003):
   *Bad first argument %r given to super()* Used when another argument
   than the current class is given as first argument of the super
   builtin.


Refactoring checker
-------------------

Verbatim name of the checker is "refactoring".


Refactoring checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~

max-nested-blocks:
   Maximum number of nested blocks for function / method body

   Default: "5"

never-returning-functions:
   Complete name of functions that never returns. When checking for
   inconsistent-return-statements if a never returning function is
   called then it will be considered as an explicit return statement
   and no message will be printed.

   Default: "sys.exit,argparse.parse_error"


Refactoring checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

simplifiable-condition (R1726):
   *Boolean condition '%s' may be simplified to '%s'* Emitted when a
   boolean condition is able to be simplified.

condition-evals-to-constant (R1727):
   *Boolean condition '%s' will always evaluate to '%s'* Emitted when
   a boolean condition can be simplified to a constant value.

simplify-boolean-expression (R1709):
   *Boolean expression may be simplified to %s* Emitted when redundant
   pre-python 2.5 ternary syntax is used.

consider-using-in (R1714):
   *Consider merging these comparisons with "in" to %r* To check if a
   variable is equal to one of many values,combine the values into a
   tuple and check if the variable is contained "in" it instead of
   checking for equality against each of the values.This is faster and
   less verbose.

consider-merging-isinstance (R1701):
   *Consider merging these isinstance calls to isinstance(%s, (%s))*
   Used when multiple consecutive isinstance calls can be merged into
   one.

consider-using-max-builtin (R1731):
   *Consider using '%s' instead of unnecessary if block* Using the max
   builtin instead of a conditional improves readability and
   conciseness.

consider-using-min-builtin (R1730):
   *Consider using '%s' instead of unnecessary if block* Using the min
   builtin instead of a conditional improves readability and
   conciseness.

consider-using-with (R1732):
   *Consider using 'with' for resource-allocating operations* Emitted
   if a resource-allocating assignment or call may be replaced by a
   'with' block. By using 'with' the release of the allocated
   resources is ensured even in the case of an exception.

super-with-arguments (R1725):
   *Consider using Python 3 style super() without arguments* Emitted
   when calling the super() builtin with the current class and
   instance. On Python 3 these arguments are the default and they can
   be omitted.

use-list-literal (R1734):
   *Consider using [] instead of list()* Emitted when using list() to
   create an empty list instead of the literal []. The literal is
   faster as it avoids an additional function call.

consider-using-dict-comprehension (R1717):
   *Consider using a dictionary comprehension* Emitted when we detect
   the creation of a dictionary using the dict() callable and a
   transient list. Although there is nothing syntactically wrong with
   this code, it is hard to read and can be simplified to a dict
   comprehension.Also it is faster since you don't need to create
   another transient list

consider-using-generator (R1728):
   *Consider using a generator instead '%s(%s)'* If your container can
   be large using a generator will bring better performance.

consider-using-set-comprehension (R1718):
   *Consider using a set comprehension* Although there is nothing
   syntactically wrong with this code, it is hard to read and can be
   simplified to a set comprehension.Also it is faster since you don't
   need to create another transient list

consider-using-get (R1715):
   *Consider using dict.get for getting values from a dict if a key is
   present or a default if not* Using the builtin dict.get for getting
   a value from a dictionary if a key is present or a default if not,
   is simpler and considered more idiomatic, although sometimes a bit
   slower

consider-using-join (R1713):
   *Consider using str.join(sequence) for concatenating strings from
   an iterable* Using str.join(sequence) is faster, uses less memory
   and increases readability compared to for-loop iteration.

consider-using-sys-exit (R1722):
   *Consider using sys.exit()* Instead of using exit() or quit(),
   consider using the sys.exit().

consider-using-ternary (R1706):
   *Consider using ternary (%s)* Used when one of known pre-python 2.5
   ternary syntax is used.

consider-swap-variables (R1712):
   *Consider using tuple unpacking for swapping variables* You do not
   have to use a temporary variable in order to swap variables. Using
   "tuple unpacking" to directly swap variables makes the intention
   more clear.

use-dict-literal (R1735):
   *Consider using {} instead of dict()* Emitted when using dict() to
   create an empty dictionary instead of the literal {}. The literal
   is faster as it avoids an additional function call.

trailing-comma-tuple (R1707):
   *Disallow trailing comma tuple* In Python, a tuple is actually
   created by the comma symbol, not by the parentheses. Unfortunately,
   one can actually create a tuple by misplacing a trailing comma,
   which can lead to potential weird bugs in your code. You should
   always use parentheses explicitly for creating a tuple.

stop-iteration-return (R1708):
   *Do not raise StopIteration in generator, use return statement
   instead* According to PEP479, the raise of StopIteration to end the
   loop of a generator may lead to hard to find bugs. This PEP specify
   that raise StopIteration has to be replaced by a simple return
   statement

inconsistent-return-statements (R1710):
   *Either all return statements in a function should return an
   expression, or none of them should.* According to PEP8, if any
   return statement returns an expression, any return statements where
   no value is returned should explicitly state this as return None,
   and an explicit return statement should be present at the end of
   the function (if reachable)

redefined-argument-from-local (R1704):
   *Redefining argument with the local name %r* Used when a local name
   is redefining an argument, which might suggest a potential error.
   This is taken in account only for a handful of name binding
   operations, such as for iteration, with statement assignment and
   exception handler assignment.

chained-comparison (R1716):
   *Simplify chained comparison between the operands* This message is
   emitted when pylint encounters boolean operation like"a < b and b <
   c", suggesting instead to refactor it to "a < b < c"

simplifiable-if-expression (R1719):
   *The if expression can be replaced with %s* Used when an if
   expression can be replaced with 'bool(test)'.

simplifiable-if-statement (R1703):
   *The if statement can be replaced with %s* Used when an if
   statement can be replaced with 'bool(test)'.

too-many-nested-blocks (R1702):
   *Too many nested blocks (%s/%s)* Used when a function or a method
   has too many nested blocks. This makes the code less understandable
   and maintainable.

no-else-break (R1723):
   *Unnecessary "%s" after "break"* Used in order to highlight an
   unnecessary block of code following an if containing a break
   statement. As such, it will warn when it encounters an else
   following a chain of ifs, all of them containing a break statement.

no-else-continue (R1724):
   *Unnecessary "%s" after "continue"* Used in order to highlight an
   unnecessary block of code following an if containing a continue
   statement. As such, it will warn when it encounters an else
   following a chain of ifs, all of them containing a continue
   statement.

no-else-raise (R1720):
   *Unnecessary "%s" after "raise"* Used in order to highlight an
   unnecessary block of code following an if containing a raise
   statement. As such, it will warn when it encounters an else
   following a chain of ifs, all of them containing a raise statement.

no-else-return (R1705):
   *Unnecessary "%s" after "return"* Used in order to highlight an
   unnecessary block of code following an if containing a return
   statement. As such, it will warn when it encounters an else
   following a chain of ifs, all of them containing a return
   statement.

unnecessary-dict-index-lookup (R1733):
   *Unnecessary dictionary index lookup, use '%s' instead* Emitted
   when iterating over the dictionary items (key-item pairs) and
   accessing the value by index lookup. The value can be accessed
   directly instead.

unnecessary-comprehension (R1721):
   *Unnecessary use of a comprehension, use %s instead.* Instead of
   using an identity comprehension, consider using the list, dict or
   set constructor. It is faster and simpler.

use-a-generator (R1729):
   *Use a generator instead '%s(%s)'* Comprehension inside of 'any' or
   'all' is unnecessary. A generator would be sufficient and faster.

useless-return (R1711):
   *Useless return at end of function or method* Emitted when a single
   "return" or "return None" statement is found at the end of function
   or method definition. This statement can safely be removed because
   Python will implicitly return None

use-implicit-booleaness-not-comparison (C1803):
   *'%s' can be simplified to '%s' as an empty sequence is falsey*
   Used when Pylint detects that collection literal comparison is
   being used to check for emptiness; Use implicit booleaness
   insteadof a collection classes; empty collections are considered as
   false

unneeded-not (C0113):
   *Consider changing "%s" to "%s"* Used when a boolean expression
   contains an unneeded negation.

consider-iterating-dictionary (C0201):
   *Consider iterating the dictionary directly instead of calling
   .keys()* Emitted when the keys of a dictionary are iterated through
   the ".keys()" method or when ".keys()" is used for a membership
   check. It is enough to iterate through the dictionary itself, "for
   key in dictionary". For membership checks, "if key in dictionary"
   is faster.

consider-using-dict-items (C0206):
   *Consider iterating with .items()* Emitted when iterating over the
   keys of a dictionary and accessing the value by index lookup. Both
   the key and value can be accessed by iterating using the .items()
   method of the dictionary instead.

consider-using-enumerate (C0200):
   *Consider using enumerate instead of iterating with range and len*
   Emitted when code that iterates with range and len is encountered.
   Such code can be simplified by using the enumerate builtin.

use-implicit-booleaness-not-len (C1802):
   *Do not use `len(SEQUENCE)` without comparison to determine if a
   sequence is empty* Used when Pylint detects that len(sequence) is
   being used without explicit comparison inside a condition to
   determine if a sequence is empty. Instead of coercing the length to
   a boolean, either rely on the fact that empty sequences are false
   or compare the length against a scalar.

consider-using-f-string (C0209):
   *Formatting a regular string which could be a f-string* Used when
   we detect a string that is being formatted with format() or % which
   could potentially be a f-string. The use of f-strings is preferred.
   Requires Python 3.6 and "py-version >= 3.6".

use-maxsplit-arg (C0207):
   *Use %s instead* Emitted when accessing only the first or last
   element of str.split(). The first and last element can be accessed
   by using str.split(sep, maxsplit=1)[0] or str.rsplit(sep,
   maxsplit=1)[-1] instead.

use-sequence-for-iteration (C0208):
   *Use a sequence type when iterating over values* When iterating
   over values, sequence types (e.g., "lists", "tuples", "ranges") are
   more efficient than "sets".


Similarities checker
--------------------

Verbatim name of the checker is "similarities".


Similarities checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

min-similarity-lines:
   Minimum lines number of a similarity.

   Default: "4"

ignore-comments:
   Comments are removed from the similarity computation

   Default: "yes"

ignore-docstrings:
   Docstrings are removed from the similarity computation

   Default: "yes"

ignore-imports:
   Imports are removed from the similarity computation

ignore-signatures:
   Signatures are removed from the similarity computation


Similarities checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

duplicate-code (R0801):
   *Similar lines in %s files* Indicates that a set of similar lines
   has been detected among multiple file. This usually means that the
   code should be refactored to avoid this duplication.


Similarities checker Reports
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

RP0801:
   Duplication


Spelling checker
----------------

Verbatim name of the checker is "spelling".


Spelling checker Options
~~~~~~~~~~~~~~~~~~~~~~~~

spelling-dict:
   Spelling dictionary name. Available dictionaries: .

spelling-ignore-words:
   List of comma separated words that should not be checked.

spelling-private-dict-file:
   A path to a file that contains the private dictionary; one word per
   line.

spelling-store-unknown-words:
   Tells whether to store unknown words to the private dictionary (see
   the --spelling-private-dict-file option) instead of raising a
   message.

max-spelling-suggestions:
   Limits count of emitted suggestions for spelling mistakes.

   Default: "4"

spelling-ignore-comment-directives:
   List of comma separated words that should be considered directives
   if they appear and the beginning of a comment and should not be
   checked.

   Default: "fmt: on,fmt: off,noqa:,noqa,nosec,isort:skip,mypy:"


Spelling checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~

invalid-characters-in-docstring (C0403):
   *Invalid characters %r in a docstring* Used when a word in
   docstring cannot be checked by enchant.

wrong-spelling-in-comment (C0401):
   *Wrong spelling of a word '%s' in a comment:* Used when a word in
   comment is not spelled correctly.

wrong-spelling-in-docstring (C0402):
   *Wrong spelling of a word '%s' in a docstring:* Used when a word in
   docstring is not spelled correctly.


Stdlib checker
--------------

Verbatim name of the checker is "stdlib".


Stdlib checker Messages
~~~~~~~~~~~~~~~~~~~~~~~

invalid-envvar-value (E1507):
   *%s does not support %s type argument* Env manipulation functions
   support only string type arguments. See
   https://docs.python.org/3/library/os.html#os.getenv.

bad-open-mode (W1501):
   *"%s" is not a valid mode for open.* Python supports: r, w, a[, x]
   modes with b, +, and U (only with r) options. See
   https://docs.python.org/2/library/functions.html#open

invalid-envvar-default (W1508):
   *%s default type is %s. Expected str or None.* Env manipulation
   functions return None or str values. Supplying anything different
   as a default may cause bugs. See
   https://docs.python.org/3/library/os.html#os.getenv.

forgotten-debug-statement (W1515):
   *Leaving functions creating breakpoints in production code is not
   recommended* Calls to breakpoint(), sys.breakpointhook() and
   pdb.set_trace() should be removed from code that is not actively
   being debugged.

redundant-unittest-assert (W1503):
   *Redundant use of %s with constant value %r* The first argument of
   assertTrue and assertFalse is a condition. If a constant is passed
   as parameter, that condition will be always true. In this case a
   warning should be emitted.

shallow-copy-environ (W1507):
   *Using copy.copy(os.environ). Use os.environ.copy() instead.*
   os.environ is not a dict object but proxy object, so shallow copy
   has still effects on original object. See
   https://bugs.python.org/issue15373 for reference.

boolean-datetime (W1502):
   *Using datetime.time in a boolean context.* Using datetime.time in
   a boolean context can hide subtle bugs when the time they represent
   matches midnight UTC. This behaviour was fixed in Python 3.5. See
   https://bugs.python.org/issue13936 for reference. This message
   can't be emitted when using Python >= 3.5.

deprecated-argument (W1511):
   *Using deprecated argument %s of method %s()* The argument is
   marked as deprecated and will be removed in the future.

deprecated-class (W1512):
   *Using deprecated class %s of module %s* The class is marked as
   deprecated and will be removed in the future.

deprecated-decorator (W1513):
   *Using deprecated decorator %s()* The decorator is marked as
   deprecated and will be removed in the future.

deprecated-method (W1505):
   *Using deprecated method %s()* The method is marked as deprecated
   and will be removed in a future version of Python. Consider looking
   for an alternative in the documentation.

unspecified-encoding (W1514):
   *Using open without explicitly specifying an encoding* It is better
   to specify an encoding when opening documents. Using the system
   default implicitly can create problems on other operating systems.
   See https://www.python.org/dev/peps/pep-0597/

subprocess-popen-preexec-fn (W1509):
   *Using preexec_fn keyword which may be unsafe in the presence of
   threads* The preexec_fn parameter is not safe to use in the
   presence of threads in your application. The child process could
   deadlock before exec is called. If you must use it, keep it
   trivial! Minimize the number of libraries you call
   into.https://docs.python.org/3/library/subprocess.html#popen-
   constructor

subprocess-run-check (W1510):
   *Using subprocess.run without explicitly set `check` is not
   recommended.* The check parameter should always be used with
   explicitly set *check* keyword to make clear what the error-
   handling behavior
   is.https://docs.python.org/3/library/subprocess.html#subprocess.run

bad-thread-instantiation (W1506):
   *threading.Thread needs the target function* The warning is emitted
   when a threading.Thread class is instantiated without the target
   function being passed. By default, the first parameter is the group
   param, not the target param.


String checker
--------------

Verbatim name of the checker is "string".


String checker Options
~~~~~~~~~~~~~~~~~~~~~~

check-str-concat-over-line-jumps:
   This flag controls whether the implicit-str-concat should generate
   a warning on implicit string concatenation in sequences defined
   over several lines.

check-quote-consistency:
   This flag controls whether inconsistent-quotes generates a warning
   when the character used as a quote delimiter is used inconsistently
   within a module.


String checker Messages
~~~~~~~~~~~~~~~~~~~~~~~

bad-string-format-type (E1307):
   *Argument %r does not match format type %r* Used when a type
   required by format string is not suitable for actual argument type

format-needs-mapping (E1303):
   *Expected mapping for format string, not %s* Used when a format
   string that uses named conversion specifiers is used with an
   argument that is not a mapping.

truncated-format-string (E1301):
   *Format string ends in middle of conversion specifier* Used when a
   format string terminates before the end of a conversion specifier.

missing-format-string-key (E1304):
   *Missing key %r in format string dictionary* Used when a format
   string that uses named conversion specifiers is used with a
   dictionary that doesn't contain all the keys required by the format
   string.

mixed-format-string (E1302):
   *Mixing named and unnamed conversion specifiers in format string*
   Used when a format string contains both named (e.g. '%(foo)d') and
   unnamed (e.g. '%d') conversion specifiers. This is also used when a
   named conversion specifier contains * for the minimum field width
   and/or precision.

too-few-format-args (E1306):
   *Not enough arguments for format string* Used when a format string
   that uses unnamed conversion specifiers is given too few arguments

bad-str-strip-call (E1310):
   *Suspicious argument in %s.%s call* The argument to a
   str.{l,r,}strip call contains a duplicate character,

too-many-format-args (E1305):
   *Too many arguments for format string* Used when a format string
   that uses unnamed conversion specifiers is given too many
   arguments.

bad-format-character (E1300):
   *Unsupported format character %r (%#02x) at index %d* Used when an
   unsupported format character is used in a format string.

anomalous-unicode-escape-in-string (W1402):
   *Anomalous Unicode escape in byte string: '%s'. String constant
   might be missing an r or u prefix.* Used when an escape like u is
   encountered in a byte string where it has no effect.

anomalous-backslash-in-string (W1401):
   *Anomalous backslash in string: '%s'. String constant might be
   missing an r prefix.* Used when a backslash is in a literal string
   but not as an escape.

duplicate-string-formatting-argument (W1308):
   *Duplicate string formatting argument %r, consider passing as named
   argument* Used when we detect that a string formatting is repeating
   an argument instead of using named string arguments

format-combined-specification (W1305):
   *Format string contains both automatic field numbering and manual
   field specification* Used when a PEP 3101 format string contains
   both automatic field numbering (e.g. '{}') and manual field
   specification (e.g. '{0}').

bad-format-string-key (W1300):
   *Format string dictionary key should be a string, not %s* Used when
   a format string that uses named conversion specifiers is used with
   a dictionary whose keys are not all strings.

implicit-str-concat (W1404):
   *Implicit string concatenation found in %s* String literals are
   implicitly concatenated in a literal iterable definition : maybe a
   comma is missing ?

bad-format-string (W1302):
   *Invalid format string* Used when a PEP 3101 format string is
   invalid.

missing-format-attribute (W1306):
   *Missing format attribute %r in format specifier %r* Used when a
   PEP 3101 format string uses an attribute specifier ({0.length}),
   but the argument passed for formatting doesn't have that attribute.

missing-format-argument-key (W1303):
   *Missing keyword argument %r for format string* Used when a PEP
   3101 format string that uses named fields doesn't receive one or
   more required keywords.

inconsistent-quotes (W1405):
   *Quote delimiter %s is inconsistent with the rest of the file*
   Quote delimiters are not used consistently throughout a module
   (with allowances made for avoiding unnecessary escaping).

redundant-u-string-prefix (W1406):
   *The u prefix for strings is no longer necessary in Python >=3.0*
   Used when we detect a string with a u prefix. These prefixes were
   necessary in Python 2 to indicate a string was Unicode, but since
   Python 3.0 strings are Unicode by default.

unused-format-string-argument (W1304):
   *Unused format argument %r* Used when a PEP 3101 format string that
   uses named fields is used with an argument that is not required by
   the format string.

unused-format-string-key (W1301):
   *Unused key %r in format string dictionary* Used when a format
   string that uses named conversion specifiers is used with a
   dictionary that contains keys not required by the format string.

f-string-without-interpolation (W1309):
   *Using an f-string that does not have any interpolated variables*
   Used when we detect an f-string that does not use any interpolation
   variables, in which case it can be either a normal string or a bug
   in the code.

format-string-without-interpolation (W1310):
   *Using formatting for a string that does not have any interpolated
   variables* Used when we detect a string that does not have any
   interpolation variables, in which case it can be either a normal
   string without formatting or a bug in the code.

invalid-format-index (W1307):
   *Using invalid lookup key %r in format specifier %r* Used when a
   PEP 3101 format string uses a lookup specifier ({a[1]}), but the
   argument passed for formatting doesn't contain or doesn't have that
   key as an attribute.


Threading checker
-----------------

Verbatim name of the checker is "threading".


Threading checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~

useless-with-lock (W2101):
   *'%s()' directly created in 'with' has no effect* Used when a new
   lock instance is created by using with statement which has no
   effect. Instead, an existing instance should be used to acquire
   lock.


Typecheck checker
-----------------

Verbatim name of the checker is "typecheck".


Typecheck checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~

ignore-on-opaque-inference:
   This flag controls whether pylint should warn about no-member and
   similar checks whenever an opaque object is returned when
   inferring. The inference can return multiple potential results
   while evaluating a Python object, but some branches might not be
   evaluated, which results in partial inference. In that case, it
   might be useful to still emit no-member and other checks for the
   rest of the inferred objects.

   Default: "yes"

mixin-class-rgx:
   Regex pattern to define which classes are considered mixins ignore-
   mixin- members is set to 'yes'

   Default: ".*[Mm]ixin"

ignore-mixin-members:
   Tells whether missing members accessed in mixin class should be
   ignored. A class is considered mixin if its name matches the mixin-
   class-rgx option.

   Default: "yes"

ignore-none:
   Tells whether to warn about missing members when the owner of the
   attribute is inferred to be None.

   Default: "yes"

ignored-modules:
   List of module names for which member attributes should not be
   checked (useful for modules/projects where namespaces are
   manipulated during runtime and thus existing member attributes
   cannot be deduced by static analysis). It supports qualified module
   names, as well as Unix pattern matching.

ignored-classes:
   List of class names for which member attributes should not be
   checked (useful for classes with dynamically set attributes). This
   supports the use of qualified names.

   Default: "optparse.Values,thread._local,_thread._local"

generated-members:
   List of members which are set dynamically and missed by pylint
   inference system, and so shouldn't trigger E1101 when accessed.
   Python regular expressions are accepted.

contextmanager-decorators:
   List of decorators that produce context managers, such as
   contextlib.contextmanager. Add to this list to register other
   decorators that produce valid context managers.

   Default: "contextlib.contextmanager"

missing-member-hint-distance:
   The minimum edit distance a name should have in order to be
   considered a similar match for a missing member name.

   Default: "1"

missing-member-max-choices:
   The total number of similar names that should be taken in
   consideration when showing a hint for a missing member.

   Default: "1"

missing-member-hint:
   Show a hint with possible names when a member name was not found.
   The aspect of finding the hint is based on edit distance.

   Default: "yes"

signature-mutators:
   List of decorators that change the signature of a decorated
   function.


Typecheck checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~

unsupported-assignment-operation (E1137):
   *%r does not support item assignment* Emitted when an object does
   not support item assignment (i.e. doesn't define __setitem__
   method).

unsupported-delete-operation (E1138):
   *%r does not support item deletion* Emitted when an object does not
   support item deletion (i.e. doesn't define __delitem__ method).

invalid-unary-operand-type (E1130):
   Emitted when a unary operand is used on an object which does not
   support this type of operation.

unsupported-binary-operation (E1131):
   Emitted when a binary arithmetic operation between two operands is
   not supported.

no-member (E1101):
   *%s %r has no %r member%s* Used when a variable is accessed for an
   unexistent member.

not-callable (E1102):
   *%s is not callable* Used when an object being called has been
   inferred to a non callable object.

await-outside-async (E1142):
   *'await' should be used within an async function* Emitted when
   await is used outside an async function.

redundant-keyword-arg (E1124):
   *Argument %r passed by position and keyword in %s call* Used when a
   function call would result in assigning multiple values to a
   function parameter, one value from a positional argument and one
   from a keyword argument.

assignment-from-no-return (E1111):
   *Assigning result of a function call, where the function has no
   return* Used when an assignment is done on a function call but the
   inferred function doesn't return anything.

assignment-from-none (E1128):
   *Assigning result of a function call, where the function returns
   None* Used when an assignment is done on a function call but the
   inferred function returns nothing but None.

not-context-manager (E1129):
   *Context manager '%s' doesn't implement __enter__ and __exit__.*
   Used when an instance in a with statement doesn't implement the
   context manager protocol(__enter__/__exit__).

unhashable-dict-key (E1140):
   *Dict key is unhashable* Emitted when a dict key is not hashable
   (i.e. doesn't define __hash__ method).

repeated-keyword (E1132):
   *Got multiple values for keyword argument %r in function call*
   Emitted when a function call got multiple values for a keyword.

invalid-metaclass (E1139):
   *Invalid metaclass %r used* Emitted whenever we can detect that a
   class is using, as a metaclass, something which might be invalid
   for using as a metaclass.

missing-kwoa (E1125):
   *Missing mandatory keyword argument %r in %s call* Used when a
   function call does not pass a mandatory keyword-only argument.

no-value-for-parameter (E1120):
   *No value for argument %s in %s call* Used when a function call
   passes too few arguments.

not-an-iterable (E1133):
   *Non-iterable value %s is used in an iterating context* Used when a
   non-iterable value is used in place where iterable is expected

not-a-mapping (E1134):
   *Non-mapping value %s is used in a mapping context* Used when a
   non-mapping value is used in place where mapping is expected

invalid-sequence-index (E1126):
   *Sequence index is not an int, slice, or instance with __index__*
   Used when a sequence type is indexed with an invalid type. Valid
   types are ints, slices, and objects with an __index__ method.

invalid-slice-index (E1127):
   *Slice index is not an int, None, or instance with __index__* Used
   when a slice index is not an integer, None, or an object with an
   __index__ method.

too-many-function-args (E1121):
   *Too many positional arguments for %s call* Used when a function
   call passes too many positional arguments.

unexpected-keyword-arg (E1123):
   *Unexpected keyword argument %r in %s call* Used when a function
   call passes a keyword argument that doesn't correspond to one of
   the function's parameter names.

dict-iter-missing-items (E1141):
   *Unpacking a dictionary in iteration without calling .items()*
   Emitted when trying to iterate through a dict without calling
   .items()

unsupported-membership-test (E1135):
   *Value '%s' doesn't support membership test* Emitted when an
   instance in membership test expression doesn't implement membership
   protocol (__contains__/__iter__/__getitem__).

unsubscriptable-object (E1136):
   *Value '%s' is unsubscriptable* Emitted when a subscripted value
   doesn't support subscription (i.e. doesn't define __getitem__
   method or __class_getitem__ for a class).

keyword-arg-before-vararg (W1113):
   *Keyword argument before variable positional arguments list in the
   definition of %s function* When defining a keyword argument before
   variable positional arguments, one can end up in having multiple
   values passed for the aforementioned parameter in case the method
   is called with keyword arguments.

non-str-assignment-to-dunder-name (W1115):
   *Non-string value assigned to __name__* Emitted when a non-string
   value is assigned to __name__

arguments-out-of-order (W1114):
   *Positional arguments appear to be out of order* Emitted when the
   caller's argument names fully match the parameter names in the
   function signature but do not have the same order.

isinstance-second-argument-not-valid-type (W1116):
   *Second argument of isinstance is not a type* Emitted when the
   second argument of an isinstance call is not a type.

c-extension-no-member (I1101):
   *%s %r has no %r member%s, but source is unavailable. Consider
   adding this module to extension-pkg-allow-list if you want to
   perform analysis based on run-time introspection of living
   objects.* Used when a variable is accessed for non-existent member
   of C extension. Due to unavailability of source static analysis is
   impossible, but it may be performed by introspecting living objects
   in run-time.


Unsupported Version checker
---------------------------

Verbatim name of the checker is "unsupported_version".


Unsupported Version checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

using-f-string-in-unsupported-version (W1601):
   *F-strings are not supported by all versions included in the py-
   version setting* Used when the py-version set by the user is lower
   than 3.6 and pylint encounters a f-string.

using-final-decorator-in-unsupported-version (W1602):
   *typing.final is not supported by all versions included in the py-
   version setting* Used when the py-version set by the user is lower
   than 3.8 and pylint encounters a "typing.final" decorator.


Variables checker
-----------------

Verbatim name of the checker is "variables".


Variables checker Options
~~~~~~~~~~~~~~~~~~~~~~~~~

init-import:
   Tells whether we should check for unused import in __init__ files.

dummy-variables-rgx:
   A regular expression matching the name of dummy variables (i.e.
   expected to not be used).

   Default:
   "_+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy|^ignored_|^unused_"

additional-builtins:
   List of additional names supposed to be defined in builtins.
   Remember that you should avoid defining new builtins when possible.

callbacks:
   List of strings which can identify a callback function by name. A
   callback name must start or end with one of those strings.

   Default: "cb_,_cb"

redefining-builtins-modules:
   List of qualified module names which can have objects that can
   redefine builtins.

   Default: "six.moves,past.builtins,future.builtins,builtins,io"

ignored-argument-names:
   Argument names that match this expression will be ignored. Default
   to name with leading underscore.

   Default: "_.*|^ignored_|^unused_"

allow-global-unused-variables:
   Tells whether unused global variables should be treated as a
   violation.

   Default: "yes"

allowed-redefined-builtins:
   List of names allowed to shadow builtins


Variables checker Messages
~~~~~~~~~~~~~~~~~~~~~~~~~~

unpacking-non-sequence (E0633):
   *Attempting to unpack a non-sequence%s* Used when something which
   is not a sequence is used in an unpack assignment

invalid-all-format (E0605):
   *Invalid format for __all__, must be tuple or list* Used when
   __all__ has an invalid format.

invalid-all-object (E0604):
   *Invalid object %r in __all__, must contain only strings* Used when
   an invalid (non-string) object occurs in __all__.

no-name-in-module (E0611):
   *No name %r in module %r* Used when a name cannot be found in a
   module.

undefined-variable (E0602):
   *Undefined variable %r* Used when an undefined variable is
   accessed.

undefined-all-variable (E0603):
   *Undefined variable name %r in __all__* Used when an undefined
   variable name is referenced in __all__.

used-before-assignment (E0601):
   *Using variable %r before assignment* Used when a local variable is
   accessed before its assignment.

cell-var-from-loop (W0640):
   *Cell variable %s defined in loop* A variable used in a closure is
   defined in a loop. This will result in all closures using the same
   value for the closed-over variable.

global-variable-undefined (W0601):
   *Global variable %r undefined at the module level* Used when a
   variable is defined through the "global" statement but the variable
   is not defined in the module scope.

self-cls-assignment (W0642):
   *Invalid assignment to %s in method* Invalid assignment to self or
   cls in instance or class method respectively.

unbalanced-tuple-unpacking (W0632):
   *Possible unbalanced tuple unpacking with sequence%s: left side has
   %d label(s), right side has %d value(s)* Used when there is an
   unbalanced tuple unpacking in assignment

possibly-unused-variable (W0641):
   *Possibly unused variable %r* Used when a variable is defined but
   might not be used. The possibility comes from the fact that
   locals() might be used, which could consume or not the said
   variable

redefined-builtin (W0622):
   *Redefining built-in %r* Used when a variable or function override
   a built-in.

redefined-outer-name (W0621):
   *Redefining name %r from outer scope (line %s)* Used when a
   variable's name hides a name defined in the outer scope.

unused-import (W0611):
   *Unused %s* Used when an imported module or variable is not used.

unused-argument (W0613):
   *Unused argument %r* Used when a function or method argument is not
   used.

unused-wildcard-import (W0614):
   *Unused import(s) %s from wildcard import of %s* Used when an
   imported module or variable is not used from a *'from X import *'*
   style import.

unused-variable (W0612):
   *Unused variable %r* Used when a variable is defined but not used.

global-variable-not-assigned (W0602):
   *Using global for %r but no assignment is done* Used when a
   variable is defined through the "global" statement but no
   assignment to this variable is done.

undefined-loop-variable (W0631):
   *Using possibly undefined loop variable %r* Used when a loop
   variable (i.e. defined by a for loop or a list comprehension or a
   generator expression) is used outside the loop.

global-statement (W0603):
   *Using the global statement* Used when you use the "global"
   statement to update a global variable. Pylint just try to
   discourage this usage. That doesn't mean you cannot use it !

global-at-module-level (W0604):
   *Using the global statement at the module level* Used when you use
   the "global" statement at the module level since it has no effect
