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pylint features

this document is generated with *pylint --full-documentation*. It describes pylint options, checking messages and reports.

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 <file or directory> to the black list. It should be a base name, not a path. You may set this option multiple times.

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.
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.
disable:Disable 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).

Reports options

output-format:

Set the output format. Available formats are text, parseable, colorized, msvs (visual studio) and html

Default: text
include-ids:

Include message's id in output
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).

logging checker

Messages

W6501: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/.

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

Messages

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

R0801:Duplication

string_format checker

Messages

E9900:Unsupported format character %r (%#02x) at index %d Used when a unsupported format character is used in a format string.
E9901:Format string ends in middle of conversion specifier Used when a format string terminates before the end of a conversion specifier.
E9902: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.
E9903: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.
E9904: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.
E9905:Too many arguments for format string Used when a format string that uses unnamed conversion specifiers is given too few arguments.
E9906:Not enough arguments for format string Used when a format string that uses unnamed conversion specifiers is given too many arguments
W9900: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.
W9901: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.

format checker

Options

max-line-length:
 

Maximum number of characters on a single line.

Default: 80
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

W0301:Unnecessary semicolon Used when a statement is ended by a semi-colon (";"), which isn't necessary (that's python, not C ;).
W0311:Bad indentation. Found %s %s, expected %s Used when an unexpected number of indentation's tabulations or spaces has been found.
W0312:Found indentation with %ss instead of %ss Used when there are some mixed tabs and spaces in a module.
W0331:Use of the <> operator Used when the deprecated "<>" operator is used instead of "!=".
W0332:Use 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"
W0333:Use of the `` operator Used when the deprecated "``" (backtick) operator is used instead of the str() function.
C0301:Line too long (%s/%s) Used when a line is longer than a given number of characters.
C0302:Too many lines in module (%s) Used when a module has too much lines, reducing its readability.
C0321:More than one statement on a single line Used when more than on statement are found on the same line.
C0322:Operator not preceded by a space Used when one of the following operator (!= | <= | == | >= | < | > | = | += | -= | *= | /= | %) is not preceded by a space.
C0323:Operator not followed by a space Used when one of the following operator (!= | <= | == | >= | < | > | = | += | -= | *= | /= | %) is not followed by a space.
C0324:Comma not followed by a space Used when a comma (",") is not followed by a space.
F0321:Format detection error in %r Used when an unexpected error occurred in bad format detection.Please report the error if it occurs.

imports checker

Options

deprecated-modules:
 

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

Default: regsub,string,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

W0401:Wildcard import %s Used when from module import * is detected.
W0402:Uses of a deprecated module %r Used a module marked as deprecated is imported.
W0403:Relative import %r, should be %r Used when an import relative to the package directory is detected.
W0404:Reimport %r (imported line %s) Used when a module is reimported multiple times.
W0406:Module import itself Used when a module is importing itself.
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.
R0401:Cyclic import (%s) Used when a cyclic import between two or more modules is detected.
F0401:Unable to import %r Used when pylint has been unable to import a module.

Reports

RP0401:External dependencies
RP0402:Modules dependencies graph

variables checker

Options

init-import:

Tells whether we should check for unused import in __init__ files.
dummy-variables-rgx:
 

A regular expression matching the beginning of the name of dummy variables (i.e. 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

E0601:

Using variable %r before assignment Used when a local variable is accessed before it's assignment.
E0602:

Undefined variable %r Used when an undefined variable is accessed.
E0611:

No name %r in module %r Used when a name cannot be found in a module.
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.
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.
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 !
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
W0611:

Unused import %s Used when an imported module or variable is not used.
W0612:

Unused variable %r Used when a variable is defined but not used.
W0613:

Unused argument %r Used when a function or method argument is not used.
W0614:

Unused import %s from wildcard import Used when an imported module or variable is not used from a 'from X import *' style import.

ReST / HTML errors:System Message: WARNING/2 (&lt;string&gt; , line 315); <em>backlink</em></p>

Inline emphasis start-string without end-string.
W0621:

Redefining name %r from outer scope (line %s) Used when a variable's name hide a name defined in the outer scope.
W0622:

Redefining built-in %r Used when a variable or function override a built-in.
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.

miscellaneous checker

Options

notes:

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

Default: FIXME,XXX,TODO

Messages

E0501:Non ascii characters found but no encoding specified (PEP 263) Used when some non ascii characters are detected but now encoding is specified, as explicited in the PEP 263.
E0502:Wrong encoding specified (%s) Used when a known encoding is specified but the file doesn't seem to be actually in this encoding.
E0503:Unknown encoding specified (%s) Used when an encoding is specified, but it's unknown to Python.
W0511:Used when a warning note as FIXME or XXX is detected.

metrics checker

Reports

RP0701:Raw metrics

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

Messages

E0202:An attribute inherited from %s hide this method Used when a class defines a method which is hidden by an instance attribute from an ancestor class.
E0203:Access to member %r before its definition line %s Used when an instance member is accessed before it's actually assigned.
E0211:Method has no argument Used when a method which should have the bound instance as first argument has no argument defined.
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!
E0221:Interface resolved to %s is not a class Used when a class claims to implement an interface which is not a class.
E0222:Missing method %r from %s interface Used when a method declared in an interface is missing from a class implementing this interface
W0201:Attribute %r defined outside __init__ Used when an instance attribute is defined outside the __init__ method.
W0211:Static method with %r as first argument Used when a static method has "self" or "cls" as first argument.
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.
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.
W0222:Signature differs from %s method Used when a method signature is different than in the implemented interface or in an overridden 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.
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.
W0232:Class has no __init__ method Used when a class has no __init__ method, neither its parent classes.
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.
R0201:Method could be a function Used when a method doesn't use its bound instance, and so could be written as a function.
C0202:Class method should have "cls" as first argument Used when a class method has an attribute different than "cls" as first argument, to easily differentiate them from regular instance methods.
C0203:Metaclass method should have "mcs" as first argument Used when a metaclass method has an attribute different the "mcs" as first argument.
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.
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-branchs:

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

R0901:Too many ancestors (%s/%s) Used when class has too many parent classes, try to reduce this to get a more simple (and so easier to use) class.
R0902:Too many instance attributes (%s/%s) Used when class has too many instance attributes, try to reduce this to get a more simple (and so easier to use) class.
R0903:Too few public methods (%s/%s) Used when class has too few public methods, so be sure it's really worth it.
R0904:Too many public methods (%s/%s) Used when class has too many public methods, try to reduce this to get a more simple (and so easier to use) class.
R0911:Too many return statements (%s/%s) Used when a function or method has too many return statement, making it hard to follow.
R0912:Too many branches (%s/%s) Used when a function or method has too many branches, making it hard to follow.
R0913:Too many arguments (%s/%s) Used when a function or method takes too many arguments.
R0914:Too many local variables (%s/%s) Used when a function or method has too many local variables.
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.
R0921:Abstract class not referenced Used when an abstract class is not used as ancestor anywhere.
R0922:Abstract class is only referenced %s times Used when an abstract class is used less than X times as ancestor.
R0923:Interface not implemented Used when an interface class is not implemented anywhere.

basic checker

Options

module-rgx:

Regular expression which should only match correct module names

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

Regular expression which should only match correct module level names

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

Regular expression which should only match correct class names

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

Regular expression which should only match correct function names

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

Regular expression which should only match correct method names

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

Regular expression which should only match correct instance attribute names

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

Regular expression which should only match correct argument names

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

Regular expression which should only match correct variable names

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

Regular expression which should only match correct list comprehension / generator expression variable names

Default: [A-Za-z_][A-Za-z0-9_]*$
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
no-docstring-rgx:
 

Regular expression which should only match functions or classes name which do not require a docstring

Default: __.*__
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

Messages

E0100:__init__ method is a generator Used when the special class method __init__ is turned into a generator by a yield in its body.
E0101:Explicit return in __init__ Used when the special class method __init__ has an explicit return value.
E0102:%s already defined line %s Used when a function / class / method is redefined.
E0103:%r not properly in loop Used when break or continue keywords are used outside a loop.
E0104:Return outside function Used when a "return" statement is found outside a function or method.
E0105:Yield outside function Used when a "yield" statement is found outside a function or method.
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).
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.
W0101:Unreachable code Used when there is some code behind a "return" or "raise" statement, which will never be accessed.
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.
W0104:Statement seems to have no effect Used when a statement doesn't have (or at least seems to) any effect.
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.
W0107:Unnecessary pass statement Used when a "pass" statement that can be avoided is encountered.)
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.
W0109:Duplicate key %r in dictionary Used when a dictionary expression binds the same key multiple times.
W0122:Use of the exec statement Used when you use the "exec" statement, to discourage its usage. That doesn't mean you can not use it !
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.
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.
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.
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.
C0102:Black listed name "%s" Used when the name is listed in the black list (unauthorized names).
C0103:Invalid name "%s" (should match %s) Used when the name doesn't match the regular expression associated to its type (constant, variable, class...).
C0111:Missing docstring Used when a module, function, class or method has no docstring. Some special methods like __init__ doesn't necessary require a docstring.
C0112:Empty docstring Used when a module, function, class or method has an empty docstring (it would be too easy ;).
C0121:Missing required attribute "%s" Used when an attribute required for modules is missing.

Reports

RP0101:Statistics by type

exceptions checker

Messages

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.
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).
E0710:Raising a new style class which doesn't inherit from BaseException Used when a new style class which doesn't inherit from BaseException raised since it's not possible with python < 2.5.
E0711:NotImplemented raised - should raise NotImplementedError Used when NotImplemented is raised instead of NotImplementedError
W0701:Raising a string exception Used when a string exception is raised.
W0702:No exception type(s) specified Used when an except clause doesn't specify exceptions type to catch.
W0703:Catch "Exception" Used when an except catches Exception instances.
W0704:Except doesn't do anything Used when an except clause does nothing but "pass" and there is no "else" clause.
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.

newstyle checker

Messages

E1001:Use __slots__ on an old style class Used when an old style class use the __slots__ attribute.
E1002:Use super on an old style class Used when an old style class use the super builtin.
E1003:Bad first argument %r given to super class Used when another argument than the current class is given as first argument of the super builtin.
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

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-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.

Default: REQUEST,acl_users,aq_parent

Messages

E1101:%s %r has no %r member Used when a variable is accessed for an unexistent member.
E1102:%s is not callable Used when an object being called has been inferred to a non callable object
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 astng was not able to interpret all possible types of this variable.
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.
E1120:No value passed for parameter %s in function call Used when a function call passes too few arguments.
E1121:Too many positional arguments for function call Used when a function call passes too many positional arguments.
E1122:Duplicate keyword argument %r in function call Used when a function call passes the same keyword argument multiple times.
E1123:Passing unexpected keyword argument %r in function call Used when a function call passes a keyword argument that doesn't correspond to one of the function's parameter names.
E1124:Multiple values passed for parameter %r in function 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.
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.

Comments

  • 2010/06/02 13:42, written by anon | reply to this comment

    The similarity checker is probably a good idea. But I really would like it to be able to ignore import statements.

  • 2010/09/16 16:08, written by anon | reply to this comment

    In the Exceptions checker I would like a warning when the older form
    "raise ValueError, 'message'"
    is used instead of
    "raise ValueError('message')".

  • 2010/09/16 16:23, written by sthenault | reply to this comment

    submit ticket for feature request please

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Card #3639 - latest update on 2011/11/28, created on 2007/03/06 by Sylvain Thenault