Pylint features

Options

General options

rcfile:

Specify a configuration file.

init-hook:

Python code to execute, usually for sys.path manipulation such as pygtk.require().

errors-only:

In error mode, checkers without error messages are disabled and for others, only the ERROR messages are displayed, and no reports are done by default

profile:

Profiled execution.

ignore:

Add files or directories to the blacklist. They should be base names, not paths.

Default: CVS

persistent:

Pickle collected data for later comparisons.

Default: yes

load-plugins:

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

include-ids:

DEPRECATED

symbols:

DEPRECATED

long-help:

more verbose help.

Commands options

help-msg:Display a help message for the given message id and exit. The value may be a comma separated list of message ids.
list-msgs:Generate pylint’s messages.
full-documentation:
 Generate pylint’s full documentation.
generate-rcfile:
 Generate a sample configuration file according to the current configuration. You can put other options before this one to get them in the generated configuration.
generate-man:Generate pylint’s man page.

Messages control options

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. 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, msvs (visual studio) and html. You can also give a reporter class, eg mypackage.mymodule.MyReporterClass.

Default: text

files-output:

Put messages in a separate file for each module / package specified on the command line instead of printing them on stdout. Reports (if any) will be written in a file name “pylint_global.[txt|html]”.

reports:

Tells whether to display a full report or only the messages

Default: yes

evaluation:

Python expression which should return a note less than 10 (10 is the highest note). You have access to the variables errors warning, statement which respectively contain the number of errors / warnings messages and the total number of statements analyzed. This is used by the global evaluation report (RP0004).

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

comment:

Add a comment according to your evaluation note. This is used by the global evaluation report (RP0004).

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

logging checker

Options

logging-modules:
 

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

Default: logging

Messages

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-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-many-args (E1205):
 Too many arguments for logging format string Used when a logging format string is given too few arguments.
logging-too-few-args (E1206):
 Not enough arguments for logging format string Used when a logging format string is given too many arguments
logging-not-lazy (W1201):
 Specify string format arguments as logging function parameters Used when a logging statement has a call form of “logging.<logging method>(format_string % (format_args...))”. Such calls should leave string interpolation to the logging method itself and be written “logging.<logging method>(format_string, format_args...)” so that the program may avoid incurring the cost of the interpolation in those cases in which no message will be logged. For more, see http://www.python.org/dev/peps/pep-0282/.

string_constant checker

Messages

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.
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.

format checker

Options

max-line-length:
 

Maximum number of characters on a single line.

Default: 80

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.

no-space-check:

List of optional constructs for which whitespace checking is disabled

Default: trailing-comma,dict-separator

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: '    '

Messages

unnecessary-semicolon (W0301):
 Unnecessary semicolon Used when a statement is ended by a semi-colon (”;”), which isn’t necessary (that’s python, not C ;).
bad-indentation (W0311):
 Bad indentation. Found %s %s, expected %s Used when an unexpected number of indentation’s tabulations or spaces has been found.
mixed-indentation (W0312):
 Found indentation with %ss instead of %ss Used when there are some mixed tabs and spaces in a module.
old-ne-operator (W0331):
 Use of the <> operator Used when the deprecated “<>” operator is used instead of ”!=”.
lowercase-l-suffix (W0332):
 Use of “l” as long integer identifier Used when a lower case “l” is used to mark a long integer. You should use a upper case “L” since the letter “l” looks too much like the digit “1”
backtick (W0333):
 Use of the `` operator Used when the deprecated “``” (backtick) operator is used instead of the str() function.
line-too-long (C0301):
 Line too long (%s/%s) Used when a line is longer than a given number of characters.
too-many-lines (C0302):
 Too many lines in module (%s) Used when a module has too much lines, reducing its readability.
trailing-whitespace (C0303):
 Trailing whitespace Used when there is whitespace between the end of a line and the newline.
missing-final-newline (C0304):
 Final newline missing Used when the last line in a file is missing a newline.
multiple-statements (C0321):
 More than one statement on a single line Used when more than on statement are found on the same line.
superfluous-parens (C0325):
 Unnecessary parens after %r keyword Used when a single item in parentheses follows an if, for, or other keyword.
bad-whitespace (C0326):
 %s space %s %s %s Used when a wrong number of spaces is used around an operator, bracket or block opener.

typecheck checker

Options

ignore-mixin-members:
 

Tells whether missing members accessed in mixin class should be ignored. A mixin class is detected if its name ends with “mixin” (case insensitive).

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 extisting member attributes cannot be deduced by static analysis

ignored-classes:
 

List of classes names for which member attributes should not be checked (useful for classes with attributes dynamically set).

Default: SQLObject

zope:

When zope mode is activated, add a predefined set of Zope acquired attributes to generated-members.

generated-members:
 

List of members which are set dynamically and missed by pylint inference system, and so shouldn’t trigger E0201 when accessed. Python regular expressions are accepted.

Default: REQUEST,acl_users,aq_parent

Messages

no-member (E1101):
 %s %r has no %r member 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
maybe-no-member (E1103):
 %s %r has no %r member (but some types could not be inferred) Used when a variable is accessed for an unexistent member, but astroid was not able to interpret all possible types of this variable.
assignment-from-no-return (E1111):
 Assigning to function call which doesn’t return Used when an assignment is done on a function call but the inferred function doesn’t return anything.
no-value-for-parameter (E1120):
 No value for argument %s in %s call Used when a function call passes too few arguments.
too-many-function-args (E1121):
 Too many positional arguments for %s call Used when a function call passes too many positional arguments.
duplicate-keyword-arg (E1122):
 Duplicate keyword argument %r in %s call Used when a function call passes the same keyword argument multiple times. This message can’t be emitted when using Python >= 2.6.
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.
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.
missing-kwoa (E1125):
 Missing mandatory keyword argument %r in %s call Used when a function call does not pass a mandatory keyword-only argument. This message can’t be emitted when using Python < 3.0.
assignment-from-none (W1111):
 Assigning to function call which only returns None Used when an assignment is done on a function call but the inferred function returns nothing but None.

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. expectedly not used).

Default: _$|dummy

additional-builtins:
 

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

Messages

used-before-assignment (E0601):
 Using variable %r before assignment Used when a local variable is accessed before it’s assignment.
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__.
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.
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.
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.
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 can not 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
unused-import (W0611):
 Unused import %s Used when an imported module or variable is not used.
unused-variable (W0612):
 Unused variable %r Used when a variable is defined but 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 from wildcard import Used when an imported module or variable is not used from a ‘from X import *‘ style import.
redefined-outer-name (W0621):
 Redefining name %r from outer scope (line %s) Used when a variable’s name hide a name defined in the outer scope.
redefined-builtin (W0622):
 Redefining built-in %r Used when a variable or function override a built-in.
redefine-in-handler (W0623):
 Redefining name %r from %s in exception handler Used when an exception handler assigns the exception to an existing name
undefined-loop-variable (W0631):
 Using possibly undefined loop variable %r Used when an loop variable (i.e. defined by a for loop or a list comprehension or a generator expression) is used outside the loop.
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
unpacking-non-sequence (W0633):
 Attempting to unpack a non-sequence%s Used when something which is not a sequence is used in an unpack assignment

basic checker

Options

required-attributes:
 

Required attributes for module, separated by a comma

bad-functions:

List of builtins function names that should not be used, separated by a comma

Default: map,filter,apply,input,file

good-names:

Good variable names which should always be accepted, separated by a comma

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

bad-names:

Bad variable names which should always be refused, separated by a comma

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

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

function-rgx:

Regular expression matching correct function names

Default: [a-z_][a-z0-9_]{2,30}$

function-name-hint:
 

Naming hint for function names

Default: [a-z_][a-z0-9_]{2,30}$

variable-rgx:

Regular expression matching correct variable names

Default: [a-z_][a-z0-9_]{2,30}$

variable-name-hint:
 

Naming hint for variable names

Default: [a-z_][a-z0-9_]{2,30}$

const-rgx:

Regular expression matching correct constant names

Default: (([A-Z_][A-Z0-9_]*)|(__.*__))$

const-name-hint:
 

Naming hint for constant names

Default: (([A-Z_][A-Z0-9_]*)|(__.*__))$

attr-rgx:

Regular expression matching correct attribute names

Default: [a-z_][a-z0-9_]{2,30}$

attr-name-hint:

Naming hint for attribute names

Default: [a-z_][a-z0-9_]{2,30}$

argument-rgx:

Regular expression matching correct argument names

Default: [a-z_][a-z0-9_]{2,30}$

argument-name-hint:
 

Naming hint for argument names

Default: [a-z_][a-z0-9_]{2,30}$

class-attribute-rgx:
 

Regular expression matching correct class attribute names

Default: ([A-Za-z_][A-Za-z0-9_]{2,30}|(__.*__))$

class-attribute-name-hint:
 

Naming hint for class attribute names

Default: ([A-Za-z_][A-Za-z0-9_]{2,30}|(__.*__))$

inlinevar-rgx:

Regular expression matching correct inline iteration names

Default: [A-Za-z_][A-Za-z0-9_]*$

inlinevar-name-hint:
 

Naming hint for inline iteration names

Default: [A-Za-z_][A-Za-z0-9_]*$

class-rgx:

Regular expression matching correct class names

Default: [A-Z_][a-zA-Z0-9]+$

class-name-hint:
 

Naming hint for class names

Default: [A-Z_][a-zA-Z0-9]+$

module-rgx:

Regular expression matching correct module names

Default: (([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$

module-name-hint:
 

Naming hint for module names

Default: (([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$

method-rgx:

Regular expression matching correct method names

Default: [a-z_][a-z0-9_]{2,30}$

method-name-hint:
 

Naming hint for method names

Default: [a-z_][a-z0-9_]{2,30}$

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

Messages

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.
return-in-init (E0101):
 Explicit return in __init__ Used when the special class method __init__ has an explicit return value.
function-redefined (E0102):
 %s already defined line %s Used when a function / class / method is redefined.
not-in-loop (E0103):
 %r not properly in loop Used when break or continue keywords are used outside a loop.
return-outside-function (E0104):
 Return outside function Used when a “return” statement is found outside a function or method.
yield-outside-function (E0105):
 Yield outside function Used when a “yield” 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.
nonexistent-operator (E0107):
 Use of the non-existent %s operator Used when you attempt to use the C-style pre-increment orpre-decrement operator – and ++, which doesn’t exist in Python.
duplicate-argument-name (E0108):
 Duplicate argument name %s in function definition Duplicate argument names in function definitions are syntax errors.
missing-reversed-argument (E0109):
 Missing argument to reversed() Used when reversed() builtin didn’t receive an argument.
abstract-class-instantiated (E0110):
 Abstract class with abstract methods instantiated Used when an abstract class with abc.ABCMeta as metaclass has abstract methods and is instantiated. This message can’t be emitted when using Python < 3.0.
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__
unreachable (W0101):
 Unreachable code Used when there is some code behind a “return” or “raise” statement, which will never be accessed.
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.
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.
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.
unnecessary-pass (W0107):
 Unnecessary pass statement Used when a “pass” statement that can be avoided is encountered.
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.
duplicate-key (W0109):
 Duplicate key %r in dictionary Used when a dictionary expression binds the same key multiple times.
deprecated-lambda (W0110):
 map/filter on lambda could be replaced by comprehension Used when a lambda is the first argument to “map” or “filter”. It could be clearer as a list comprehension or generator expression. This message can’t be emitted when using Python >= 3.0.
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.
old-raise-syntax (W0121):
 Use raise ErrorClass(args) instead of raise ErrorClass, args. Used when the alternate raise syntax ‘raise foo, bar’ is used instead of ‘raise foo(bar)’. This message can’t be emitted when using Python >= 3.0.
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 can not use it !
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.
bad-builtin (W0141):
 Used builtin function %r Used when a black listed builtin function is used (see the bad-function option). Usual black listed functions are the ones like map, or filter , where Python offers now some cleaner alternative like list comprehension.
star-args (W0142):
 Used * or * magic* Used when a function or method is called using *args or **kwargs to dispatch arguments. This doesn’t improve readability and should be used with care.
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-uple. 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.
blacklisted-name (C0102):
 Black listed name “%s” Used when the name is listed in the black list (unauthorized names).
invalid-name (C0103):
 Invalid %s name “%s”%s Used when the name doesn’t match the regular expression associated to its type (constant, variable, class...).
missing-docstring (C0111):
 Missing %s docstring Used when a module, function, class or method has no docstring. Some special methods like __init__ doesn’t necessary require a docstring.
empty-docstring (C0112):
 Empty %s docstring Used when a module, function, class or method has an empty docstring (it would be too easy ;).
missing-module-attribute (C0121):
 Missing required attribute “%s” Used when an attribute required for modules is missing.

Reports

RP0101:Statistics by type

miscellaneous checker

Options

notes:

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

Default: FIXME,XXX,TODO

Messages

fixme (W0511):Used when a warning note as FIXME or XXX is detected.
invalid-encoded-data (W0512):
 Cannot decode using encoding “%s”, unexpected byte at position %d Used when a source line cannot be decoded using the specified source file encoding. This message can’t be emitted when using Python >= 3.0.

open_mode checker

Messages

bad-open-mode (W1501):
 “%s” is not a valid mode for open. Python supports: r, w, a modes with b, +, and U options. See http://docs.python.org/2/library/functions.html#open

metrics checker

Reports

RP0701:Raw metrics

imports checker

Options

deprecated-modules:
 

Deprecated modules which should not be used, separated by a comma

Default: regsub,TERMIOS,Bastion,rexec

import-graph:

Create a graph of every (i.e. internal and external) dependencies in the given file (report RP0402 must not be disabled)

ext-import-graph:
 

Create a graph of external dependencies in the given file (report RP0402 must not be disabled)

int-import-graph:
 

Create a graph of internal dependencies in the given file (report RP0402 must not be disabled)

Messages

wildcard-import (W0401):
 Wildcard import %s Used when from module import * is detected.
deprecated-module (W0402):
 Uses of a deprecated module %r Used a module marked as deprecated is imported.
relative-import (W0403):
 Relative import %r, should be %r Used when an import relative to the package directory is detected.
reimported (W0404):
 Reimport %r (imported line %s) Used when a module is reimported multiple times.
import-self (W0406):
 Module import itself Used when a module is importing itself.
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. This message can’t be emitted when using Python >= 3.0.
cyclic-import (R0401):
 Cyclic import (%s) Used when a cyclic import between two or more modules is detected.
import-error (F0401):
 Unable to import %s Used when pylint has been unable to import a module.

Reports

RP0401:External dependencies
RP0402:Modules dependencies graph

classes checker

Options

ignore-iface-methods:
 

List of interface methods to ignore, separated by a comma. This is used for instance to not check methods defines in Zope’s Interface base class.

Default: isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by

defining-attr-methods:
 

List of method names used to declare (i.e. assign) instance attributes.

Default: __init__,__new__,setUp

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: mcs

Messages

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.
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.
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!
interface-is-not-class (E0221):
 Interface resolved to %s is not a class Used when a class claims to implement an interface which is not a class.
missing-interface-method (E0222):
 Missing method %r from %s interface Used when a method declared in an interface is missing from a class implementing this interface
bad-context-manager (E0235):
 __exit__ must accept 3 arguments: type, value, traceback Used when the __exit__ special method, belonging to a context manager, does not accept 3 arguments (type, value, traceback).
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__.
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.
attribute-defined-outside-init (W0201):
 Attribute %r defined outside __init__ Used when an instance attribute is defined outside the __init__ 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.
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.
arguments-differ (W0221):
 Arguments number differs from %s method Used when a method has a different number of arguments than in the implemented interface or in an overridden method.
signature-differs (W0222):
 Signature differs from %s method Used when a method signature is different than in the implemented interface or in an overridden method.
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.
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.
no-init (W0232):
 Class has no __init__ method Used when a class has no __init__ method, neither its parent classes.
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.
non-iterator-returned (W0234):
 __iter__ returns non-iterator Used when an __iter__ method returns something which is not an iterable (i.e. has no next method)
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.
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-method-argument (C0203):
 Metaclass method %s should have %s as first argument Used when a metaclass method has a first agument 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.
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.
unresolved-interface (F0220):
 failed to resolve interfaces implemented by %s (%s) Used when a PyLint as failed to find interfaces implemented by a class

design checker

Options

max-args:

Maximum number of arguments for function / method

Default: 5

ignored-argument-names:
 

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

Default: _.*

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

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

Messages

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-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-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-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-branches (R0912):
 Too many branches (%s/%s) Used when a function or method has too many branches, making it hard to follow.
too-many-arguments (R0913):
 Too many arguments (%s/%s) Used when a function or method takes too many arguments.
too-many-locals (R0914):
 Too many local variables (%s/%s) Used when a function or method has too many local variables.
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.
abstract-class-not-used (R0921):
 Abstract class not referenced Used when an abstract class is not used as ancestor anywhere.
abstract-class-little-used (R0922):
 Abstract class is only referenced %s times Used when an abstract class is used less than X times as ancestor.
interface-not-implemented (R0923):
 Interface not implemented Used when an interface class is not implemented anywhere.

similarities checker

Options

min-similarity-lines:
 

Minimum lines number of a similarity.

Default: 4

ignore-comments:
 

Ignore comments when computing similarities.

Default: yes

ignore-docstrings:
 

Ignore docstrings when computing similarities.

Default: yes

ignore-imports:

Ignore imports when computing similarities.

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.

Reports

RP0801:Duplication

exceptions checker

Options

overgeneral-exceptions:
 

Exceptions that will emit a warning when being caught. Defaults to “Exception”

Default: Exception

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 catched by the most specific handler.
raising-bad-type (E0702):
 Raising %s while only classes, instances or string are allowed Used when something which is neither a class, an instance or a string is raised (i.e. a TypeError will be raised).
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. This message can’t be emitted when using Python < 3.0.
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.
notimplemented-raised (E0711):
 NotImplemented raised - should raise NotImplementedError Used when NotImplemented is raised instead of NotImplementedError
catching-non-exception (E0712):
 Catching an exception which doesn’t inherit from BaseException: %s Used when a class which doesn’t inherit from BaseException is used as an exception in an except clause.
raising-string (W0701):
 Raising a string exception Used when a string exception is raised.
bare-except (W0702):
 No exception type(s) specified Used when an except clause doesn’t specify exceptions type to catch.
broad-except (W0703):
 Catching too general exception %s Used when an except catches a too general exception, possibly burying unrelated errors.
pointless-except (W0704):
 Except doesn’t do anything Used when an except clause does nothing but “pass” and there is no “else” clause.
nonstandard-exception (W0710):
 Exception doesn’t inherit from standard “Exception” class Used when a custom exception class is raised but doesn’t inherit from the builtin “Exception” class. This message can’t be emitted when using Python >= 3.0.
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):”
unpacking-in-except (W0712):
 Implicit unpacking of exceptions is not supported in Python 3 Python3 will not allow implicit unpacking of exceptions in except clauses. See http://www.python.org/dev/peps/pep-3110/ This message can’t be emitted when using Python >= 3.0.

newstyle checker

Messages

slots-on-old-class (E1001):
 Use of __slots__ on an old style class Used when an old style class uses the __slots__ attribute. This message can’t be emitted when using Python >= 3.0.
super-on-old-class (E1002):
 Use of super on an old style class Used when an old style class uses the super builtin. This message can’t be emitted when using Python >= 3.0.
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.
missing-super-argument (E1004):
 Missing argument to super() Used when the super builtin didn’t receive an argument. This message can’t be emitted when using Python >= 3.0.
property-on-old-class (W1001):
 Use of “property” on an old style class Used when PyLint detect the use of the builtin “property” on an old style class while this is relying on new style classes features. This message can’t be emitted when using Python >= 3.0.
old-style-class (C1001):
 Old-style class defined. Used when a class is defined that does not inherit from anotherclass and does not inherit explicitly from “object”. This message can’t be emitted when using Python >= 3.0.

string checker

Messages

bad-format-character (E1300):
 Unsupported format character %r (%#02x) at index %d Used when a unsupported format character is used in a format string.
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.
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.
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.
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.
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.
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,
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.
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 conWtains keys not required by the format string.