PyLint features
PyLint features
1. Contents
  • Link or reference ("general-options") to an inexistant target. General options
  • Link or reference ("commands-options") to an inexistant target. Commands options
  • Link or reference ("messages-control-options") to an inexistant target. Messages control options
  • Link or reference ("reports-options") to an inexistant target. Reports options
  • Link or reference ("main-messages") to an inexistant target. Main messages
  • Link or reference ("main-reports") to an inexistant target. Main reports
    • Link or reference ("basic-checker") to an inexistant target. Basic checker
  • Link or reference ("options") to an inexistant target. Options
  • Link or reference ("messages") to an inexistant target. Messages
  • Link or reference ("reports") to an inexistant target. Reports
    • Link or reference ("typecheck-checker") to an inexistant target. Typecheck checker
  • Link or reference ("id1") to an inexistant target. Options
  • Link or reference ("id2") to an inexistant target. Messages
    • Link or reference ("variables-checker") to an inexistant target. Variables checker
  • Link or reference ("id3") to an inexistant target. Options
  • Link or reference ("id4") to an inexistant target. Messages
    • Link or reference ("classes-checker") to an inexistant target. Classes checker
  • Link or reference ("id7") to an inexistant target. Options
  • Link or reference ("id8") to an inexistant target. Messages
    • Link or reference ("design-checker") to an inexistant target. Design checker
  • Link or reference ("id9") to an inexistant target. Options
  • Link or reference ("id10") to an inexistant target. Messages
    • Link or reference ("imports-checker") to an inexistant target. Imports checker
  • Link or reference ("id11") to an inexistant target. Options
  • Link or reference ("id12") to an inexistant target. Messages
  • Link or reference ("id13") to an inexistant target. Reports
    • Link or reference ("newstyle-checker") to an inexistant target. Newstyle checker
  • Link or reference ("id14") to an inexistant target. Messages
    • Link or reference ("exceptions-checker") to an inexistant target. Exceptions checker
  • Link or reference ("id15") to an inexistant target. Messages
    • Link or reference ("format-checker") to an inexistant target. Format checker
  • Link or reference ("id16") to an inexistant target. Options
  • Link or reference ("id17") to an inexistant target. Messages
    • Link or reference ("miscellaneous-checker") to an inexistant target. Miscellaneous checker
  • Link or reference ("id18") to an inexistant target. Options
  • Link or reference ("id19") to an inexistant target. Messages
    • Link or reference ("metrics-checker") to an inexistant target. Metrics checker
  • Link or reference ("id20") to an inexistant target. Reports
    • Link or reference ("similarities-checker") to an inexistant target. Similarities checker
  • Link or reference ("id21") to an inexistant target. Options
  • Link or reference ("id22") to an inexistant target. Messages
  • Link or reference ("id23") to an inexistant target. Reports
2. General options
rcfile
Specify a configuration file.
init-hook
Python code to execute, usually for sys.path manipulation such as pygtk.require().
rpython-mode
enable the rpython checker which is disabled by default
errors-only
In debug 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
cache-size
Set the cache size for astng objects. Default: 500
load-plugins
List of plugins (as comma separated values of python modules names) to load, usually to register additional checkers.
3. 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 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.
4. Messages control options
enable-checker
Enable only checker(s) with the given id(s). This option conflicts with the disable-checker option
disable-checker
Enable all checker(s) except those with the given id(s). This option conflicts with the enable-checker option
enable-msg-cat
Enable all messages in the listed categories.
disable-msg-cat
Disable all messages in the listed categories.
enable-msg
Enable the message(s) with the given id(s).
disable-msg
Disable the message(s) with the given id(s).
5. 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 wether 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 respectivly contain the number of errors / warnings messages and the total number of statements analyzed. This is used by the global evaluation report (R0004). 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 (R0004).
enable-report
Enable the report(s) with the given id(s).
disable-report
Disable the report(s) with the given id(s).
6. Main messages
E0001
Used when a syntax error is raised for a module.
E0011
Unrecognized file option %r Used when an unknown inline option is encountered.
E0012
Bad option value %r Used when a bad value for an inline option is encountered.
I0001
Unable to run raw checkers on built-in module %s Used to inform that a built-in module has not been checked using the raw checkers.
I0010
Unable to consider inline option %r Used when an inline option is either badly formatted or can't be used inside modules.
I0011
Locally disabling %s Used when an inline option disables a message or a messages category.
I0012
Locally enabling %s Used when an inline option enables a message or a messages category.
I0013
Ignoring entire file Used to inform that the file will not be checked
F0001
Used when an error occured preventing the analysis of a module (unable to find it for instance).
F0002
%s: %s Used when an unexpected error occured while building the ASTNG representation. This is usually accompanied by a traceback. Please report such errors !
F0003
ignored builtin module %s Used to indicate that the user asked to analyze a builtin module which has been skipped.
F0004
unexpected infered value %s Used to indicate that some value of an unexpected type has been infered.
7. Main reports
R0001
Messages by category
R0002
% errors / warnings by module
R0003
Messages
R0004
Global evaluation
7.1. Basic checker
checks for : * doc strings * modules / classes / functions / methods / arguments / variables name * number of arguments, local variables, branchs, returns and statements in functions, methods * required module attributes * dangerous default values as arguments * redefinition of function / method / class * uses of the global statement
8. Options
required-attributes
Required attributes for module, separated by a comma
no-docstring-rgx
Regular expression which should only match functions or classes name which do not require a docstring Default: __.*__
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-Z1-9_]*)|(__.*__))$
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
bad-functions
List of builtins function names that should not be used, separated by a comma Default: map,filter,apply,input
9. 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).
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.
W0106
Unnecessary semicolon Used when a statement is endend by a semi-colon (";"), which isn't necessary (that's python, not C ;).
W0107
Unnecessary pass statement Used when a "pass" statement that can be avoided is encountered.)
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.
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.
10. Reports
R0101
Statistics by type
10.1. Typecheck checker
try to find bugs in the code using type inference
11. Options
ignore-mixin-members
Tells wether 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 dynamicaly set). Default: SQLObject
zope
When zope mode is activated, consider the acquired-members option to ignore access to some undefined attributes.
acquired-members
List of members which are usually get through zope's acquisition mecanism and so shouldn't trigger E0201 when accessed (need zope=yes to be considered). Default: REQUEST,acl_users,aq_parent
12. Messages
E1101
%s %r has no %r member Used when a variable is accessed for an unexistant member.
E1102
%s is not callable Used when an object being called has been infered 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 unexistant 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 assigment is done on a function call but the infered function doesn't return anything.
W1111
Assigning to function call which only returns None Used when an assigment is done on a function call but the infered function returns nothing but None.
12.1. Variables checker
checks for * unused variables / imports * undefined variables * redefinition of variable from builtins or from an outer scope * use of variable before assigment
13. Options
init-import
Tells wether we should check for unused import in __init__ files.
dummy-variables-rgx
A regular expression matching names used for 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.
14. 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 assigment is done Used when a variable is defined through the "global" statement but no assigment 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.
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.
14.1. Classes checker
checks for : * methods without self as first argument * overridden methods signature * access only to existant members via self * attributes not defined in the __init__ method * supported interfaces implementation * unreachable code
15. 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
16. Messages
E0202
An attribute inherited from %s hide this method Used when a class defines a method which is hiden 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 soooo common convention that you should'nt 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 (ie 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 raison. 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
16.1. Design checker
checks for sign of poor/misdesign: * number of methods, attributes, local variables... * size, complexity of functions, methods
17. 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-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
18. 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.
18.1. Imports checker
checks for * external modules dependencies * relative / wildcard imports * cyclic imports * uses of deprecated modules
19. 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 R0402 must not be disabled)
ext-import-graph
Create a graph of external dependencies in the given file (report R0402 must not be disabled)
int-import-graph
Create a graph of internal dependencies in the given file (report R0402 must not be disabled)
20. 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 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 (%s) Used when pylint has been unable to import a module.
21. Reports
R0401
External dependencies
R0402
Modules dependencies graph
21.1. Newstyle checker
checks for usage of new style capabilities on old style classes and other new/old styles conflicts problems * use of property, __slots__, super * "super" usage * raising a new style class as exception
22. 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.
E1010
Raising a new style class Used when a new style class is raised since it's not possible with python < 2.5.
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
W1010
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.
22.1. Exceptions checker
checks for * excepts without exception filter * string exceptions
23. 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).
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.
W0706
Identifier %s used to raise an exception is assigned to %s Used when a variable used to raise an exception is initially assigned to a value which can't be used as an exception.
23.1. Format checker
checks for : * unauthorized constructions * strict indentation * line length * use of <> instead of !=
24. 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: ' '
25. Messages
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 readibility.
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 occured in bad format detection.Please report the error if it occurs.
25.1. Miscellaneous checker
checks for: * warning notes in the code like FIXME, XXX * PEP 263: source code with non ascii character but no encoding declaration
26. Options
notes
List of note tags to take in consideration, separated by a comma. Default: FIXME,XXX,TODO
27. 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.
27.1. Metrics checker
does not check anything but gives some raw metrics : * total number of lines * total number of code lines * total number of docstring lines * total number of comments lines * total number of empty lines
28. Reports
R0701
Raw metrics
28.1. Similarities checker
checks for similarities and duplicated code. This computation may be memory / CPU intensive, so you should disable it if you experiments some problems.
29. 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
30. 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.
31. Reports
R0801
Duplication
32. Docutils System Messages
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-z".
Unknown target name: "a-z1-9".
Unknown target name: "a-z".
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-z".
Unknown target name: "a-z0-9".
Unknown target name: "a-za-z".
Unknown target name: "a-za-z0-9".