Pylint features

Pylint global options and switches

Pylint provides global options and switches.

General options

ignore:

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

Default: CVS

ignore-patterns:
 

Add files or directories matching the regex patterns to the blacklist. The regex matches against base names, not paths.

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.

jobs:

Use multiple processes to speed up Pylint.

Default: 1

unsafe-load-any-extension:
 

Allow loading of arbitrary C extensions. Extensions are imported into the active Python interpreter and may run arbitrary code.

extension-pkg-whitelist:
 

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

Messages control options

confidence:

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

enable:

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

disable:

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

Default: print-statement,parameter-unpacking,unpacking-in-except,old-raise-syntax,backtick,long-suffix,old-ne-operator,old-octal-literal,import-star-module-level,apply-builtin,basestring-builtin,buffer-builtin,cmp-builtin,coerce-builtin,execfile-builtin,file-builtin,long-builtin,raw_input-builtin,reduce-builtin,standarderror-builtin,unicode-builtin,xrange-builtin,coerce-method,delslice-method,getslice-method,setslice-method,no-absolute-import,old-division,dict-iter-method,dict-view-method,next-method-called,metaclass-assignment,indexing-exception,raising-string,reload-builtin,oct-method,hex-method,nonzero-method,cmp-method,input-builtin,round-builtin,intern-builtin,unichr-builtin,map-builtin-not-iterating,zip-builtin-not-iterating,range-builtin-not-iterating,filter-builtin-not-iterating,using-cmp-argument,eq-without-hash,div-method,idiv-method,rdiv-method,exception-message-attribute,invalid-str-codec,sys-max-int,bad-python3-import,deprecated-string-function,deprecated-str-translate-call

Reports options

output-format:

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

Default: text

reports:

Tells whether to display a full report or only the messages

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)

score:

Activate the evaluation score.

Default: yes

msg-template:

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

Pylint checkers’ options and switches

Pylint checkers can provide three set of features:

  • options that control their execution,
  • messages that they can raise,
  • reports that they can generate.

Below is a list of all checkers and their features.

Logging checker

Verbatim name of the checker is logging.

Options

logging-modules:
 

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

Default: logging

Messages

logging-format-truncated (E1201):
 Logging format string ends in middle of conversion specifier Used when a logging statement format string terminates before the end of a conversion specifier.
logging-too-few-args (E1206):
 Not enough arguments for logging format string Used when a logging format string is given too few arguments.
logging-too-many-args (E1205):
 Too many arguments for logging format string Used when a logging format string is given too many arguments.
logging-unsupported-format (E1200):
 Unsupported logging format character %r (%#02x) at index %d Used when an unsupported format character is used in a logging statement format string.
logging-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/.
logging-format-interpolation (W1202):
 Use % formatting in logging functions and pass the % parameters as arguments Used when a logging statement has a call form of “logging.<logging method>(format_string.format(format_args...))”. Such calls should use % formatting instead, but leave interpolation to the logging function by passing the parameters as arguments.

Similarities checker

Verbatim name of the checker is similarities.

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

Format checker

Verbatim name of the checker is format.

Options

max-line-length:
 

Maximum number of characters on a single line.

Default: 100

ignore-long-lines:
 

Regexp for a line that is allowed to be longer than the limit.

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

single-line-if-stmt:
 

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

no-space-check:

List of optional constructs for which whitespace checking is disabled. dict- separator is used to allow tabulation in dicts, etc.: {1 : 1,n222: 2}. trailing-comma allows a space between comma and closing bracket: (a, ). empty-line allows space-only lines.

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: '    '

indent-after-paren:
 

Number of spaces of indent required inside a hanging or continued line.

Default: 4

expected-line-ending-format:
 

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

Messages

bad-indentation (W0311):
 Bad indentation. Found %s %s, expected %s Used when an unexpected number of indentation’s tabulations or spaces has been found.
mixed-indentation (W0312):
 Found indentation with %ss instead of %ss Used when there are some mixed tabs and spaces in a module.
unnecessary-semicolon (W0301):
 Unnecessary semicolon Used when a statement is ended by a semi-colon (”;”), which isn’t necessary (that’s python, not C ;).
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” This message can’t be emitted when using Python >= 3.0.
bad-whitespace (C0326):
 %s space %s %s %s Used when a wrong number of spaces is used around an operator, bracket or block opener.
missing-final-newline (C0304):
 Final newline missing Used when the last line in a file is missing a newline.
line-too-long (C0301):
 Line too long (%s/%s) Used when a line is longer than a given number of characters.
mixed-line-endings (C0327):
 Mixed line endings LF and CRLF Used when there are mixed (LF and CRLF) newline signs in a file.
multiple-statements (C0321):
 More than one statement on a single line Used when more than on statement are found on the same line.
too-many-lines (C0302):
 Too many lines in module (%s/%s) Used when a module has too much lines, reducing its readability.
trailing-newlines (C0305):
 Trailing newlines Used when there are trailing blank lines in a file.
trailing-whitespace (C0303):
 Trailing whitespace Used when there is whitespace between the end of a line and the newline.
unexpected-line-ending-format (C0328):
 Unexpected line ending format. There is ‘%s’ while it should be ‘%s’. Used when there is different newline than expected.
superfluous-parens (C0325):
 Unnecessary parens after %r keyword Used when a single item in parentheses follows an if, for, or other keyword.
bad-continuation (C0330):
 Wrong %s indentation%s%s. TODO

Imports checker

Verbatim name of the checker is imports.

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)

known-standard-library:
 

Force import order to recognize a module as part of the standard compatibility libraries.

known-third-party:
 

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

Default: enchant

analyse-fallback-blocks:
 

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

Messages

relative-beyond-top-level (E0402):
 Attempted relative import beyond top-level package Used when a relative import tries to access too many levels in the current package.
import-error (E0401):
 Unable to import %s Used when pylint has been unable to import a module.
import-self (W0406):
 Module import itself Used when a module is importing itself.
reimported (W0404):
 Reimport %r (imported line %s) Used when a module is reimported multiple times.
relative-import (W0403):
 Relative import %r, should be %r Used when an import relative to the package directory is detected. This message can’t be emitted when using Python >= 3.0.
deprecated-module (W0402):
 Uses of a deprecated module %r Used a module marked as deprecated is imported.
wildcard-import (W0401):
 Wildcard import %s Used when from module import * is detected.
misplaced-future (W0410):
 __future__ import is not the first non docstring statement Python 2.5 and greater require __future__ import to be the first non docstring statement in the module.
cyclic-import (R0401):
 Cyclic import (%s) Used when a cyclic import between two or more modules is detected.
wrong-import-order (C0411):
 %s comes before %s Used when PEP8 import order is not respected (standard imports first, then third-party libraries, then local imports)
wrong-import-position (C0413):
 Import “%s” should be placed at the top of the module Used when code and imports are mixed
ungrouped-imports (C0412):
 Imports from package %s are not grouped Used when imports are not grouped by packages
multiple-imports (C0410):
 Multiple imports on one line (%s) Used when import statement importing multiple modules is detected.

Reports

RP0401:External dependencies
RP0402:Modules dependencies graph

Variables checker

Verbatim name of the checker is variables.

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: _+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy

additional-builtins:
 

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

callbacks:

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

Default: cb_,_cb

redefining-builtins-modules:
 

List of qualified module names which can have objects that can redefine builtins.

Default: six.moves,future.builtins

ignored-argument-names:
 

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

Default: _.*

allow-global-unused-variables:
 

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

Default: yes

Messages

unpacking-non-sequence (E0633):
 Attempting to unpack a non-sequence%s Used when something which is not a sequence is used in an unpack assignment
invalid-all-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.
unbalanced-tuple-unpacking (E0632):
 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
undefined-variable (E0602):
 Undefined variable %r Used when an undefined variable is accessed.
undefined-all-variable (E0603):
 Undefined variable name %r in __all__ Used when an undefined variable name is referenced in __all__.
used-before-assignment (E0601):
 Using variable %r before assignment Used when a local variable is accessed before it’s assignment.
cell-var-from-loop (W0640):
 Cell variable %s defined in loop A variable used in a closure is defined in a loop. This will result in all closures using the same value for the closed-over variable.
global-variable-undefined (W0601):
 Global variable %r undefined at the module level Used when a variable is defined through the “global” statement but the variable is not defined in the module scope.
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
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.
unused-import (W0611):
 Unused %s Used when an imported module or variable is not used.
unused-argument (W0613):
 Unused argument %r Used when a function or method argument is not used.
unused-wildcard-import (W0614):
 Unused import %s from wildcard import Used when an imported module or variable is not used from a ‘from X import *’ style import.
unused-variable (W0612):
 Unused variable %r Used when a variable is defined but not used.
global-variable-not-assigned (W0602):
 Using global for %r but no assignment is done Used when a variable is defined through the “global” statement but no assignment to this variable is done.
undefined-loop-variable (W0631):
 Using possibly undefined loop variable %r Used when an loop variable (i.e. defined by a for loop or a list comprehension or a generator expression) is used outside the loop.
global-statement (W0603):
 Using the global statement Used when you use the “global” statement to update a global variable. Pylint just try to discourage this usage. That doesn’t mean you cannot use it !
global-at-module-level (W0604):
 Using the global statement at the module level Used when you use the “global” statement at the module level since it has no effect

Basic checker

Verbatim name of the checker is basic.

Options

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

property-classes:
 

List of decorators that produce properties, such as abc.abstractproperty. Add to this list to register other decorators that produce valid properties.

Default: abc.abstractproperty

function-rgx:

Regular expression matching correct function names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

function-name-hint:
 

Naming hint for function names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

variable-rgx:

Regular expression matching correct variable names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

variable-name-hint:
 

Naming hint for variable names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

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})|(_[a-z0-9_]*))$

attr-name-hint:

Naming hint for attribute names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

argument-rgx:

Regular expression matching correct argument names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

argument-name-hint:
 

Naming hint for argument names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

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})|(_[a-z0-9_]*))$

method-name-hint:
 

Naming hint for method names

Default: (([a-z][a-z0-9_]{2,30})|(_[a-z0-9_]*))$

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

not-in-loop (E0103):
 %r not properly in loop Used when break or continue keywords are used outside a loop.
function-redefined (E0102):
 %s already defined line %s Used when a function / class / method is redefined.
continue-in-finally (E0116):
 ‘continue’ not supported inside ‘finally’ clause Emitted when the continue keyword is found inside a finally clause, which is a SyntaxError.
abstract-class-instantiated (E0110):
 Abstract class %r with abstract methods instantiated Used when an abstract class with abc.ABCMeta as metaclass has abstract methods and is instantiated.
star-needs-assignment-target (E0114):
 Can use starred expression only in assignment target Emitted when a star expression is not used in an assignment target. This message can’t be emitted when using Python < 3.0.
duplicate-argument-name (E0108):
 Duplicate argument name %s in function definition Duplicate argument names in function definitions are syntax errors.
return-in-init (E0101):
 Explicit return in __init__ Used when the special class method __init__ has an explicit return value.
too-many-star-expressions (E0112):
 More than one starred expression in assignment Emitted when there are more than one starred expressions (*x) in an assignment. This is a SyntaxError. This message can’t be emitted when using Python < 3.0.
nonlocal-and-global (E0115):
 Name %r is nonlocal and global Emitted when a name is both nonlocal and global. This message can’t be emitted when using Python < 3.0.
return-outside-function (E0104):
 Return outside function Used when a “return” statement is found outside a function or method.
return-arg-in-generator (E0106):
 Return with argument inside generator Used when a “return” statement with an argument is found outside in a generator function or method (e.g. with some “yield” statements). This message can’t be emitted when using Python >= 3.3.
invalid-star-assignment-target (E0113):
 Starred assignment target must be in a list or tuple Emitted when a star expression is used as a starred assignment target. 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__
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.
yield-outside-function (E0105):
 Yield outside function Used when a “yield” statement is found outside a function or method.
init-is-generator (E0100):
 __init__ method is a generator Used when the special class method __init__ is turned into a generator by a yield in its body.
nonlocal-without-binding (E0117):
 nonlocal name %s found without binding Emitted when a nonlocal variable does not have an attached name somewhere in the parent scopes This message can’t be emitted when using Python < 3.0.
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.
dangerous-default-value (W0102):
 Dangerous default value %s as argument Used when a mutable value as list or dictionary is detected in a default value for an argument.
duplicate-key (W0109):
 Duplicate key %r in dictionary Used when a dictionary expression binds the same key multiple times.
useless-else-on-loop (W0120):
 Else clause on loop without a break statement Loops should only have an else clause if they can exit early with a break statement, otherwise the statements under else should be on the same scope as the loop itself.
expression-not-assigned (W0106):
 Expression “%s” is assigned to nothing Used when an expression that is not a function call is assigned to nothing. Probably something else was intended.
confusing-with-statement (W0124):
 Following “as” with another context manager looks like a tuple. Emitted when a with statement component returns multiple values and uses name binding with as only for a part of those values, as in with ctx() as a, b. This can be misleading, since it’s not clear if the context manager returns a tuple or if the node without a name binding is another context manager.
unnecessary-lambda (W0108):
 Lambda may not be necessary Used when the body of a lambda expression is a function call on the same argument list as the lambda itself; such lambda expressions are in all but a few cases replaceable with the function being called in the body of the lambda.
pointless-statement (W0104):
 Statement seems to have no effect Used when a statement doesn’t have (or at least seems to) any effect.
pointless-string-statement (W0105):
 String statement has no effect Used when a string is used as a statement (which of course has no effect). This is a particular case of W0104 with its own message so you can easily disable it if you’re using those strings as documentation, instead of comments.
unnecessary-pass (W0107):
 Unnecessary pass statement Used when a “pass” statement that can be avoided is encountered.
unreachable (W0101):
 Unreachable code Used when there is some code behind a “return” or “raise” statement, which will never be accessed.
eval-used (W0123):
 Use of eval Used when you use the “eval” function, to discourage its usage. Consider using ast.literal_eval for safely evaluating strings containing Python expressions from untrusted sources.
exec-used (W0122):
 Use of exec Used when you use the “exec” statement (function for Python 3), to discourage its usage. That doesn’t mean you cannot use it !
using-constant-test (W0125):
 Using a conditional statement with a constant value Emitted when a conditional statement (If or ternary if) uses a constant value for its test. This might not be what the user intended to do.
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.
literal-comparison (R0123):
 Comparison to literal Used when comparing an object to a literal, which is usually what you do not want to do, since you can compare to a different literal than what was expected altogether.
blacklisted-name (C0102):
 Black listed name “%s” Used when the name is listed in the black list (unauthorized names).
misplaced-comparison-constant (C0122):
 Comparison should be %s Used when the constant is placed on the left side of a comparison. It is usually clearer in intent to place it in the right hand side of the comparison.
singleton-comparison (C0121):
 Comparison to %s should be %s Used when an expression is compared to singleton values like True, False or None.
unneeded-not (C0113):
 Consider changing “%s” to “%s” Used when a boolean expression contains an unneeded negation.
empty-docstring (C0112):
 Empty %s docstring Used when a module, function, class or method has an empty docstring (it would be too easy ;).
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.
unidiomatic-typecheck (C0123):
 Using type() instead of isinstance() for a typecheck. The idiomatic way to perform an explicit typecheck in Python is to use isinstance(x, Y) rather than type(x) == Y, type(x) is Y. Though there are unusual situations where these give different results.

Reports

RP0101:Statistics by type

Miscellaneous checker

Verbatim name of the checker is miscellaneous.

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.

Len checker

Verbatim name of the checker is len.

Messages

len-as-condition (C1801):
 Do not use `len(SEQUENCE)` as condition value Used when Pylint detects incorrect use of len(sequence) inside conditions.

Metrics checker

Verbatim name of the checker is metrics.

Reports

RP0701:Raw metrics

Refactoring checker

Verbatim name of the checker is refactoring.

Options

max-nested-blocks:
 

Maximum number of nested blocks for function / method body

Default: 5

Messages

consider-merging-isinstance (R1701):
 Consider merging these isinstance calls to isinstance(%s, (%s)) Used when multiple consecutive isinstance calls can be merged into one.
consider-using-ternary (R1706):
 Consider using ternary (%s if %s else %s) Used when one of known pre-python 2.5 ternary syntax is used.
trailing-comma-tuple (R1707):
 Disallow trailing comma tuple In Python, a tuple is actually created by the comma symbol, not by the parentheses. Unfortunately, one can actually create a tuple by misplacing a trailing comma, which can lead to potential weird bugs in your code. You should always use parentheses explicitly for creating a tuple. This message can’t be emitted when using Python < 3.0.
redefined-argument-from-local (R1704):
 Redefining argument with the local name %r Used when a local name is redefining an argument, which might suggest a potential error. This is taken in account only for a handful of name binding operations, such as for iteration, with statement assignment and exception handler assignment.
simplifiable-if-statement (R1703):
 The if statement can be replaced with %s Used when an if statement can be replaced with ‘bool(test)’.
too-many-nested-blocks (R1702):
 Too many nested blocks (%s/%s) Used when a function or a method has too many nested blocks. This makes the code less understandable and maintainable.
no-else-return (R1705):
 Unnecessary “else” after “return” Used in order to highlight an unnecessary block of code following an if containing a return statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a return statement.
consider-iterating-dictionary (C0201):
 Consider iterating the dictionary directly instead of calling .keys() Emitted when the keys of a dictionary are iterated through the .keys() method. It is enough to just iterate through the dictionary itself, as in “for key in dictionary”.
consider-using-enumerate (C0200):
 Consider using enumerate instead of iterating with range and len Emitted when code that iterates with range and len is encountered. Such code can be simplified by using the enumerate builtin.

Classes checker

Verbatim name of the checker is classes.

Options

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

exclude-protected:
 

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

Default: _asdict,_fields,_replace,_source,_make

Messages

access-member-before-definition (E0203):
 Access to member %r before its definition line %s Used when an instance member is accessed before it’s actually assigned.
method-hidden (E0202):
 An attribute defined in %s line %s hides this method Used when a class defines a method which is hidden by an instance attribute from an ancestor class or set by some client code.
assigning-non-slot (E0237):
 Assigning to attribute %r not defined in class slots Used when assigning to an attribute not defined in the class slots.
duplicate-bases (E0241):
 Duplicate bases for class %r Used when a class has duplicate bases.
inconsistent-mro (E0240):
 Inconsistent method resolution order for class %r Used when a class has an inconsistent method resolution order.
inherit-non-class (E0239):
 Inheriting %r, which is not a class. Used when a class inherits from something which is not a class.
invalid-slots (E0238):
 Invalid __slots__ object Used when an invalid __slots__ is found in class. Only a string, an iterable or a sequence is permitted.
invalid-slots-object (E0236):
 Invalid object %r in __slots__, must contain only non empty strings Used when an invalid (non-string) object occurs in __slots__.
no-method-argument (E0211):
 Method has no argument Used when a method which should have the bound instance as first argument has no argument defined.
no-self-argument (E0213):
 Method should have “self” as first argument Used when a method has an attribute different the “self” as first argument. This is considered as an error since this is a so common convention that you shouldn’t break it!
unexpected-special-method-signature (E0302):
 The special method %r expects %s param(s), %d %s given Emitted when a special method was defined with an invalid number of parameters. If it has too few or too many, it might not work at all.
non-iterator-returned (E0301):
 __iter__ returns non-iterator Used when an __iter__ method returns something which is not an iterable (i.e. has no next method)
invalid-length-returned (E0303):
 __len__ does not return non-negative integer Used when an __len__ method returns something which is not a non-negative integer
protected-access (W0212):
 Access to a protected member %s of a client class Used when a protected member (i.e. class member with a name beginning with an underscore) is access outside the class or a descendant of the class where it’s defined.
attribute-defined-outside-init (W0201):
 Attribute %r defined outside __init__ Used when an instance attribute is defined outside the __init__ method.
no-init (W0232):
 Class has no __init__ method Used when a class has no __init__ method, neither its parent classes.
abstract-method (W0223):
 Method %r is abstract in class %r but is not overridden Used when an abstract method (i.e. raise NotImplementedError) is not overridden in concrete class.
arguments-differ (W0221):
 Parameters differ from %s %r 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 %r method Used when a method signature is different than in the implemented interface or in an overridden method.
bad-staticmethod-argument (W0211):
 Static method with %r as first argument Used when a static method has “self” or a value specified in valid- classmethod-first-arg option or valid-metaclass-classmethod-first-arg option as first argument.
useless-super-delegation (W0235):
 Useless super delegation in method %r Used whenever we can detect that an overridden method is useless, relying on super() delegation to do the same thing as another method from the MRO.
non-parent-init-called (W0233):
 __init__ method from a non direct base class %r is called Used when an __init__ method is called on a class which is not in the direct ancestors for the analysed class.
super-init-not-called (W0231):
 __init__ method from base class %r is not called Used when an ancestor class method has an __init__ method which is not called by a derived class.
no-classmethod-decorator (R0202):
 Consider using a decorator instead of calling classmethod Used when a class method is defined without using the decorator syntax.
no-staticmethod-decorator (R0203):
 Consider using a decorator instead of calling staticmethod Used when a static method is defined without using the decorator syntax.
no-self-use (R0201):
 Method could be a function Used when a method doesn’t use its bound instance, and so could be written as a function.
single-string-used-for-slots (C0205):
 Class __slots__ should be a non-string iterable Used when a class __slots__ is a simple string, rather than an iterable.
bad-classmethod-argument (C0202):
 Class method %s should have %s as first argument Used when a class method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to “cls”), recommended to easily differentiate them from regular instance methods.
bad-mcs-classmethod-argument (C0204):
 Metaclass class method %s should have %s as first argument Used when a metaclass class method has a first argument named differently than the value specified in valid-metaclass-classmethod-first-arg option (default to “mcs”), recommended to easily differentiate them from regular instance methods.
bad-mcs-method-argument (C0203):
 Metaclass method %s should have %s as first argument Used when a metaclass method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to “cls”), recommended to easily differentiate them from regular instance methods.
method-check-failed (F0202):
 Unable to check methods signature (%s / %s) Used when Pylint has been unable to check methods signature compatibility for an unexpected reason. Please report this kind if you don’t make sense of it.

Design checker

Verbatim name of the checker is design.

Options

max-args:

Maximum number of arguments for function / method

Default: 5

max-locals:

Maximum number of locals for function / method body

Default: 15

max-returns:

Maximum number of return / yield for function / method body

Default: 6

max-branches:

Maximum number of branch for function / method body

Default: 12

max-statements:

Maximum number of statements in function / method body

Default: 50

max-parents:

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

Default: 7

max-attributes:

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

Default: 7

min-public-methods:
 

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

Default: 2

max-public-methods:
 

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

Default: 20

max-bool-expr:

Maximum number of boolean expressions in a if statement

Default: 5

Messages

too-few-public-methods (R0903):
 Too few public methods (%s/%s) Used when class has too few public methods, so be sure it’s really worth it.
too-many-ancestors (R0901):
 Too many ancestors (%s/%s) Used when class has too many parent classes, try to reduce this to get a simpler (and so easier to use) class.
too-many-arguments (R0913):
 Too many arguments (%s/%s) Used when a function or method takes too many arguments.
too-many-boolean-expressions (R0916):
 Too many boolean expressions in if statement (%s/%s) Used when a if statement contains too many boolean expressions
too-many-branches (R0912):
 Too many branches (%s/%s) Used when a function or method has too many branches, making it hard to follow.
too-many-instance-attributes (R0902):
 Too many instance attributes (%s/%s) Used when class has too many instance attributes, try to reduce this to get a simpler (and so easier to use) class.
too-many-locals (R0914):
 Too many local variables (%s/%s) Used when a function or method has too many local variables.
too-many-public-methods (R0904):
 Too many public methods (%s/%s) Used when class has too many public methods, try to reduce this to get a simpler (and so easier to use) class.
too-many-return-statements (R0911):
 Too many return statements (%s/%s) Used when a function or method has too many return statement, making it hard to follow.
too-many-statements (R0915):
 Too many statements (%s/%s) Used when a function or method has too many statements. You should then split it in smaller functions / methods.

Python3 checker

Verbatim name of the checker is python3.

Messages

unpacking-in-except (E1603):
 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.
import-star-module-level (E1609):
 Import * only allowed at module level Used when the import star syntax is used somewhere else than the module level. This message can’t be emitted when using Python >= 3.0.
parameter-unpacking (E1602):
 Parameter unpacking specified Used when parameter unpacking is specified for a function(Python 3 doesn’t allow it) This message can’t be emitted when using Python >= 3.0.
long-suffix (E1606):
 Use of long suffix Used when “l” or “L” is used to mark a long integer. This will not work in Python 3, since int and long types have merged. This message can’t be emitted when using Python >= 3.0.
old-octal-literal (E1608):
 Use of old octal literal Used when encountering the old octal syntax, removed in Python 3. To use the new syntax, prepend 0o on the number. This message can’t be emitted when using Python >= 3.0.
old-ne-operator (E1607):
 Use of the <> operator Used when the deprecated “<>” operator is used instead of ”!=”. This is removed in Python 3. This message can’t be emitted when using Python >= 3.0.
backtick (E1605):
 Use of the `` operator Used when the deprecated “``” (backtick) operator is used instead of the str() function. This message can’t be emitted when using Python >= 3.0.
old-raise-syntax (E1604):
 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.
print-statement (E1601):
 print statement used Used when a print statement is used (print is a function in Python 3) This message can’t be emitted when using Python >= 3.0.
deprecated-string-function (W1649):
 Accessing a function method on the string module Used when accessing a string function that has been deprecated in Python 3. This message can’t be emitted when using Python >= 3.0.
metaclass-assignment (W1623):
 Assigning to a class’s __metaclass__ attribute Used when a metaclass is specified by assigning to __metaclass__ (Python 3 specifies the metaclass as a class statement argument) This message can’t be emitted when using Python >= 3.0.
next-method-called (W1622):
 Called a next() method on an object Used when an object’s next() method is called (Python 3 uses the next() built- in function) This message can’t be emitted when using Python >= 3.0.
dict-iter-method (W1620):
 Calling a dict.iter*() method Used for calls to dict.iterkeys(), itervalues() or iteritems() (Python 3 lacks these methods) This message can’t be emitted when using Python >= 3.0.
dict-view-method (W1621):
 Calling a dict.view*() method Used for calls to dict.viewkeys(), viewvalues() or viewitems() (Python 3 lacks these methods) This message can’t be emitted when using Python >= 3.0.
exception-message-attribute (W1645):
 Exception.message removed in Python 3 Used when the message attribute is accessed on an Exception. Use str(exception) instead. This message can’t be emitted when using Python >= 3.0.
eq-without-hash (W1641):
 Implementing __eq__ without also implementing __hash__ Used when a class implements __eq__ but not __hash__. In Python 2, objects get object.__hash__ as the default implementation, in Python 3 objects get None as their default __hash__ implementation if they also implement __eq__. This message can’t be emitted when using Python >= 3.0.
indexing-exception (W1624):
 Indexing exceptions will not work on Python 3 Indexing exceptions will not work on Python 3. Use exception.args[index] instead. This message can’t be emitted when using Python >= 3.0.
bad-python3-import (W1648):
 Module moved in Python 3 Used when importing a module that no longer exists in Python 3. This message can’t be emitted when using Python >= 3.0.
raising-string (W1625):
 Raising a string exception Used when a string exception is raised. This will not work on Python 3. This message can’t be emitted when using Python >= 3.0.
standarderror-builtin (W1611):
 StandardError built-in referenced Used when the StandardError built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
deprecated-str-translate-call (W1650):
 Using str.translate with deprecated deletechars parameters Used when using the deprecated deletechars parameters from str.translate. Usere.sub to remove the desired characters This message can’t be emitted when using Python >= 3.0.
using-cmp-argument (W1640):
 Using the cmp argument for list.sort / sorted Using the cmp argument for list.sort or the sorted builtin should be avoided, since it was removed in Python 3. Using either key or functools.cmp_to_key should be preferred. This message can’t be emitted when using Python >= 3.0.
cmp-method (W1630):
 __cmp__ method defined Used when a __cmp__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
coerce-method (W1614):
 __coerce__ method defined Used when a __coerce__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
delslice-method (W1615):
 __delslice__ method defined Used when a __delslice__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
div-method (W1642):
 __div__ method defined Used when a __div__ method is defined. Using __truediv__ and setting__div__ = __truediv__ should be preferred.(method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
getslice-method (W1616):
 __getslice__ method defined Used when a __getslice__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
hex-method (W1628):
 __hex__ method defined Used when a __hex__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
idiv-method (W1643):
 __idiv__ method defined Used when a __idiv__ method is defined. Using __itruediv__ and setting__idiv__ = __itruediv__ should be preferred.(method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
nonzero-method (W1629):
 __nonzero__ method defined Used when a __nonzero__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
oct-method (W1627):
 __oct__ method defined Used when a __oct__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
rdiv-method (W1644):
 __rdiv__ method defined Used when a __rdiv__ method is defined. Using __rtruediv__ and setting__rdiv__ = __rtruediv__ should be preferred.(method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
setslice-method (W1617):
 __setslice__ method defined Used when a __setslice__ method is defined (method is not used by Python 3) This message can’t be emitted when using Python >= 3.0.
apply-builtin (W1601):
 apply built-in referenced Used when the apply built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
basestring-builtin (W1602):
 basestring built-in referenced Used when the basestring built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
buffer-builtin (W1603):
 buffer built-in referenced Used when the buffer built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
cmp-builtin (W1604):
 cmp built-in referenced Used when the cmp built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
coerce-builtin (W1605):
 coerce built-in referenced Used when the coerce built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
old-division (W1619):
 division w/o __future__ statement Used for non-floor division w/o a float literal or from __future__ import division (Python 3 returns a float for int division unconditionally) This message can’t be emitted when using Python >= 3.0.
execfile-builtin (W1606):
 execfile built-in referenced Used when the execfile built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
file-builtin (W1607):
 file built-in referenced Used when the file built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
filter-builtin-not-iterating (W1639):
 filter built-in referenced when not iterating Used when the filter built-in is referenced in a non-iterating context (returns an iterator in Python 3) This message can’t be emitted when using Python >= 3.0.
no-absolute-import (W1618):
 import missing `from __future__ import absolute_import` Used when an import is not accompanied by from __future__ import absolute_import (default behaviour in Python 3) This message can’t be emitted when using Python >= 3.0.
input-builtin (W1632):
 input built-in referenced Used when the input built-in is referenced (backwards-incompatible semantics in Python 3) This message can’t be emitted when using Python >= 3.0.
intern-builtin (W1634):
 intern built-in referenced Used when the intern built-in is referenced (Moved to sys.intern in Python 3) This message can’t be emitted when using Python >= 3.0.
long-builtin (W1608):
 long built-in referenced Used when the long built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
map-builtin-not-iterating (W1636):
 map built-in referenced when not iterating Used when the map built-in is referenced in a non-iterating context (returns an iterator in Python 3) This message can’t be emitted when using Python >= 3.0.
invalid-str-codec (W1646):
 non-text encoding used in str.decode Used when using str.encode or str.decode with a non-text encoding. Use codecs module to handle arbitrary codecs. This message can’t be emitted when using Python >= 3.0.
range-builtin-not-iterating (W1638):
 range built-in referenced when not iterating Used when the range built-in is referenced in a non-iterating context (returns an iterator in Python 3) This message can’t be emitted when using Python >= 3.0.
raw_input-builtin (W1609):
 raw_input built-in referenced Used when the raw_input built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
reduce-builtin (W1610):
 reduce built-in referenced Used when the reduce built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
reload-builtin (W1626):
 reload built-in referenced Used when the reload built-in function is referenced (missing from Python 3). You can use instead imp.reload or importlib.reload. This message can’t be emitted when using Python >= 3.0.
round-builtin (W1633):
 round built-in referenced Used when the round built-in is referenced (backwards-incompatible semantics in Python 3) This message can’t be emitted when using Python >= 3.0.
sys-max-int (W1647):
 sys.maxint removed in Python 3 Used when accessing sys.maxint. Use sys.maxsize instead. This message can’t be emitted when using Python >= 3.0.
unichr-builtin (W1635):
 unichr built-in referenced Used when the unichr built-in is referenced (Use chr in Python 3) This message can’t be emitted when using Python >= 3.0.
unicode-builtin (W1612):
 unicode built-in referenced Used when the unicode built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
xrange-builtin (W1613):
 xrange built-in referenced Used when the xrange built-in function is referenced (missing from Python 3) This message can’t be emitted when using Python >= 3.0.
zip-builtin-not-iterating (W1637):
 zip built-in referenced when not iterating Used when the zip built-in is referenced in a non-iterating context (returns an iterator in Python 3) This message can’t be emitted when using Python >= 3.0.

Stdlib checker

Verbatim name of the checker is stdlib.

Messages

bad-open-mode (W1501):
 “%s” is not a valid mode for open. Python supports: r, w, a[, x] modes with b, +, and U (only with r) options. See http://docs.python.org/2/library/functions.html#open
redundant-unittest-assert (W1503):
 Redundant use of %s with constant value %r The first argument of assertTrue and assertFalse is a condition. If a constant is passed as parameter, that condition will be always true. In this case a warning should be emitted.
boolean-datetime (W1502):
 Using datetime.time in a boolean context. Using datetime.time in a boolean context can hide subtle bugs when the time they represent matches midnight UTC. This behaviour was fixed in Python 3.5. See http://bugs.python.org/issue13936 for reference. This message can’t be emitted when using Python >= 3.5.
deprecated-method (W1505):
 Using deprecated method %s() The method is marked as deprecated and will be removed in a future version of Python. Consider looking for an alternative in the documentation.

String Constant checker

Verbatim name of the checker is string_constant.

Messages

anomalous-unicode-escape-in-string (W1402):
 Anomalous Unicode escape in byte string: ‘%s’. String constant might be missing an r or u prefix. Used when an escape like u is encountered in a byte string where it has no effect.
anomalous-backslash-in-string (W1401):
 Anomalous backslash in string: ‘%s’. String constant might be missing an r prefix. Used when a backslash is in a literal string but not as an escape.

Exceptions checker

Verbatim name of the checker is exceptions.

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 caught by the most specific handler.
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.
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.
notimplemented-raised (E0711):
 NotImplemented raised - should raise NotImplementedError Used when NotImplemented is raised instead of NotImplementedError
raising-bad-type (E0702):
 Raising %s while only classes or instances are allowed Used when something which is neither a class, an instance or a string is raised (i.e. a TypeError will be raised).
raising-non-exception (E0710):
 Raising a new style class which doesn’t inherit from BaseException Used when a new style class which doesn’t inherit from BaseException is raised.
misplaced-bare-raise (E0704):
 The raise statement is not inside an except clause Used when a bare raise is not used inside an except clause. This generates an error, since there are no active exceptions to be reraised. An exception to this rule is represented by a bare raise inside a finally clause, which might work, as long as an exception is raised inside the try block, but it is nevertheless a code smell that must not be relied upon.
duplicate-except (W0705):
 Catching previously caught exception type %s Used when an except catches a type that was already caught by a previous handler.
broad-except (W0703):
 Catching too general exception %s Used when an except catches a too general exception, possibly burying unrelated errors.
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):”
bare-except (W0702):
 No exception type(s) specified Used when an except clause doesn’t specify exceptions type to catch.

Newstyle checker

Verbatim name of the checker is newstyle.

Messages

bad-super-call (E1003):
 Bad first argument %r given to super() Used when another argument than the current class is given as first argument of the super builtin.
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.
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.
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 another class and does not inherit explicitly from “object”. This message can’t be emitted when using Python >= 3.0.

Spelling checker

Verbatim name of the checker is spelling.

Options

spelling-dict:Spelling dictionary name. Available dictionaries: none. To make it working install python-enchant package.
spelling-ignore-words:
 List of comma separated words that should not be checked.
spelling-private-dict-file:
 A path to a file that contains private dictionary; one word per line.
spelling-store-unknown-words:
 Tells whether to store unknown words to indicated private dictionary in –spelling-private-dict-file option instead of raising a message.

Messages

invalid-characters-in-docstring (C0403):
 Invalid characters %r in a docstring Used when a word in docstring cannot be checked by enchant.
wrong-spelling-in-comment (C0401):
 Wrong spelling of a word ‘%s’ in a comment: Used when a word in comment is not spelled correctly.
wrong-spelling-in-docstring (C0402):
 Wrong spelling of a word ‘%s’ in a docstring: Used when a word in docstring is not spelled correctly.

Async checker

Verbatim name of the checker is async.

Messages

not-async-context-manager (E1701):
 Async context manager ‘%s’ doesn’t implement __aenter__ and __aexit__. Used when an async context manager is used with an object that does not implement the async context management protocol. This message can’t be emitted when using Python < 3.5.
yield-inside-async-function (E1700):
 Yield inside async function Used when an yield or yield from statement is found inside an async function. This message can’t be emitted when using Python < 3.5.

String checker

Verbatim name of the checker is string.

Messages

format-needs-mapping (E1303):
 Expected mapping for format string, not %s Used when a format string that uses named conversion specifiers is used with an argument that is not a mapping.
truncated-format-string (E1301):
 Format string ends in middle of conversion specifier Used when a format string terminates before the end of a conversion specifier.
missing-format-string-key (E1304):
 Missing key %r in format string dictionary Used when a format string that uses named conversion specifiers is used with a dictionary that doesn’t contain all the keys required by the format string.
mixed-format-string (E1302):
 Mixing named and unnamed conversion specifiers in format string Used when a format string contains both named (e.g. ‘%(foo)d’) and unnamed (e.g. ‘%d’) conversion specifiers. This is also used when a named conversion specifier contains * for the minimum field width and/or precision.
too-few-format-args (E1306):
 Not enough arguments for format string Used when a format string that uses unnamed conversion specifiers is given too few arguments
bad-str-strip-call (E1310):
 Suspicious argument in %s.%s call The argument to a str.{l,r,}strip call contains a duplicate character,
too-many-format-args (E1305):
 Too many arguments for format string Used when a format string that uses unnamed conversion specifiers is given too many arguments.
bad-format-character (E1300):
 Unsupported format character %r (%#02x) at index %d Used when a unsupported format character is used in a format string.
format-combined-specification (W1305):
 Format string contains both automatic field numbering and manual field specification Used when a PEP 3101 format string contains both automatic field numbering (e.g. ‘{}’) and manual field specification (e.g. ‘{0}’). This message can’t be emitted when using Python < 2.7.
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.
bad-format-string (W1302):
 Invalid format string Used when a PEP 3101 format string is invalid. This message can’t be emitted when using Python < 2.7.
missing-format-attribute (W1306):
 Missing format attribute %r in format specifier %r Used when a PEP 3101 format string uses an attribute specifier ({0.length}), but the argument passed for formatting doesn’t have that attribute. This message can’t be emitted when using Python < 2.7.
missing-format-argument-key (W1303):
 Missing keyword argument %r for format string Used when a PEP 3101 format string that uses named fields doesn’t receive one or more required keywords. This message can’t be emitted when using Python < 2.7.
unused-format-string-argument (W1304):
 Unused format argument %r Used when a PEP 3101 format string that uses named fields is used with an argument that is not required by the format string. This message can’t be emitted when using Python < 2.7.
unused-format-string-key (W1301):
 Unused key %r in format string dictionary Used when a format string that uses named conversion specifiers is used with a dictionary that contains keys not required by the format string.
invalid-format-index (W1307):
 Using invalid lookup key %r in format specifier %r Used when a PEP 3101 format string uses a lookup specifier ({a[1]}), but the argument passed for formatting doesn’t contain or doesn’t have that key as an attribute. This message can’t be emitted when using Python < 2.7.