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List of pylint human readable message ids and dev readable codes
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README.md

Readable pylint messages

Goal of the repo is to prepare and present README with list of messages. Prepared with pylint --list-msgs for pylint v2.2.2

blacklisted-name

C0102 - Black listed name "%s"

Used when the name is listed in the black list (unauthorized names).

invalid-name

C0103 - %s name "%s" doesn't conform to %s

Used when the name doesn't conform to naming rules associated to its type (constant, variable, class...).

missing-docstring

C0111 - Missing %s docstring

Used when a module, function, class or method has no docstring.Some special methods like init doesn't necessary require a docstring.

empty-docstring

C0112 - Empty %s docstring

Used when a module, function, class or method has an empty docstring (it would be too easy ;).

unneeded-not

C0113 - Consider changing "%s" to "%s"

Used when a boolean expression contains an unneeded negation.

singleton-comparison

C0121 - Comparison to %s should be %s

Used when an expression is compared to singleton values like True, False or None.

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.

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.

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.

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".

bad-classmethod-argument

C0202 - Class method %s should have %s as first argument

Used when a class method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to "cls"), recommended to easily differentiate them from regular instance methods.

bad-mcs-method-argument

C0203 - Metaclass method %s should have %s as first argument

Used when a metaclass method has a first 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.

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.

line-too-long

C0301 - Line too long (%s/%s)

Used when a line is longer than a given number of characters.

too-many-lines

C0302 - Too many lines in module (%s/%s)

Used when a module has too many lines, reducing its readability.

trailing-whitespace

C0303 - Trailing whitespace

Used when there is whitespace between the end of a line and the newline.

missing-final-newline

C0304 - Final newline missing

Used when the last line in a file is missing a newline.

trailing-newlines

C0305 - Trailing newlines

Used when there are trailing blank lines 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.

superfluous-parens

C0325 - Unnecessary parens after %r keyword

Used when a single item in parentheses follows an if, for, or other keyword.

bad-whitespace

C0326 - %s space %s %s %s

Used when a wrong number of spaces is used around an operator, bracket or block opener.

mixed-line-endings

C0327 - Mixed line endings LF and CRLF

Used when there are mixed (LF and CRLF) newline signs in a file.

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.

bad-continuation

C0330 - Wrong %s indentation%s%s.

TODO

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.

invalid-characters-in-docstring

C0403 - Invalid characters %r in a docstring

Used when a word in docstring cannot be checked by enchant.

multiple-imports

C0410 - Multiple imports on one line (%s)

Used when import statement importing multiple modules is detected.

wrong-import-order

C0411 - %s should be placed before %s

Used when PEP8 import order is not respected (standard imports first, then third-party libraries, then local imports)

ungrouped-imports

C0412 - Imports from package %s are not grouped

Used when imports are not grouped by packages

wrong-import-position

C0413 - Import "%s" should be placed at the top of the module

Used when code and imports are mixed

useless-import-alias

C0414 - Import alias does not rename original package

Used when an import alias is same as original package.e.g using import numpy as numpy instead of import numpy as np

len-as-condition

C1801 - Do not use len(SEQUENCE) to determine if a sequence is empty

Used when Pylint detects that len(sequence) is being used inside a condition to determine if a sequence is empty. Instead of comparing the length to 0, rely on the fact that empty sequences are false.

syntax-error

E0001 -

Used when a syntax error is raised for a module.

unrecognized-inline-option

E0011 - Unrecognized file option %r

Used when an unknown inline option is encountered.

bad-option-value

E0012 - Bad option value %r

Used when a bad value for an inline option is encountered.

init-is-generator

E0100 - init method is a generator

Used when the special class method init is turned into a generator by a yield in its body.

return-in-init

E0101 - Explicit return in init

Used when the special class method init has an explicit return value.

function-redefined

E0102 - %s already defined line %s

Used when a function / class / method is redefined.

not-in-loop

E0103 - %r not properly in loop

Used when break or continue keywords are used outside a loop.

return-outside-function

E0104 - Return outside function

Used when a "return" statement is found outside a function or method.

yield-outside-function

E0105 - Yield outside function

Used when a "yield" statement is found outside a function or method.

nonexistent-operator

E0107 - Use of the non-existent %s operator

Used when you attempt to use the C-style pre-increment or pre-decrement operator -- and ++, which doesn't exist in Python.

duplicate-argument-name

E0108 - Duplicate argument name %s in function definition

Duplicate argument names in function definitions are syntax errors.

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.

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

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.

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.

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.

nonlocal-and-global

E0115 - Name %r is nonlocal and global

Emitted when a name is both nonlocal and global.

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.

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

used-prior-global-declaration

E0118 - Name %r is used prior to global declaration

Emitted when a name is used prior a global declaration, which results in an error since Python 3.6. This message can't be emitted when using Python < 3.6.

misplaced-format-function

E0119 - format function is not called on str

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

method-hidden

E0202 - An attribute defined in %s line %s hides this method

Used when a class defines a method which is hidden by an instance attribute from an ancestor class or set by some client code.

access-member-before-definition

E0203 - Access to member %r before its definition line %s

Used when an instance member is accessed before it's actually assigned.

no-method-argument

E0211 - Method has no argument

Used when a method which should have the bound instance as first argument has no argument defined.

no-self-argument

E0213 - Method should have "self" as first argument

Used when a method has an attribute different the "self" as first argument. This is considered as an error since this is a so common convention that you shouldn't break it!

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.

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.

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.

inherit-non-class

E0239 - Inheriting %r, which is not a class.

Used when a class inherits from something which is not a class.

inconsistent-mro

E0240 - Inconsistent method resolution order for class %r

Used when a class has an inconsistent method resolution order.

duplicate-bases

E0241 - Duplicate bases for class %r

Used when a class has duplicate bases.

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)

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.

invalid-length-returned

E0303 - len does not return non-negative integer

Used when a len method returns something which is not a non-negative integer

import-error

E0401 - Unable to import %s

Used when pylint has been unable to import a module.

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.

used-before-assignment

E0601 - Using variable %r before assignment

Used when a local variable is accessed before its assignment.

undefined-variable

E0602 - Undefined variable %r

Used when an undefined variable is accessed.

undefined-all-variable

E0603 - Undefined variable name %r in all

Used when an undefined variable name is referenced in all.

invalid-all-object

E0604 - Invalid object %r in all, must contain only strings

Used when an invalid (non-string) object occurs in all.

no-name-in-module

E0611 - No name %r in module %r

Used when a name cannot be found in a module.

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

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.

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).

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.

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.

raising-non-exception

E0710 - Raising a new style class which doesn't inherit from BaseException

Used when a new style class which doesn't inherit from BaseException is raised.

notimplemented-raised

E0711 - NotImplemented raised - should raise NotImplementedError

Used when NotImplemented is raised instead of NotImplementedError

catching-non-exception

E0712 - Catching an exception which doesn't inherit from Exception: %s

Used when a class which doesn't inherit from Exception is used as an exception in an except clause.

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.

no-member

E1101 - %s %r has no %r member%s

Used when a variable is accessed for an unexistent member.

not-callable

E1102 - %s is not callable

Used when an object being called has been inferred to a non callable object.

assignment-from-no-return

E1111 - Assigning result of a function call, where the function has no return

Used when an assignment is done on a function call but the inferred function doesn't return anything.

no-value-for-parameter

E1120 - No value for argument %s in %s call

Used when a function call passes too few arguments.

too-many-function-args

E1121 - Too many positional arguments for %s call

Used when a function call passes too many positional arguments.

unexpected-keyword-arg

E1123 - Unexpected keyword argument %r in %s call

Used when a function call passes a keyword argument that doesn't correspond to one of the function's parameter names.

redundant-keyword-arg

E1124 - Argument %r passed by position and keyword in %s call

Used when a function call would result in assigning multiple values to a function parameter, one value from a positional argument and one from a keyword argument.

missing-kwoa

E1125 - Missing mandatory keyword argument %r in %s call

Used when a function call does not pass a mandatory keyword-only argument.

invalid-sequence-index

E1126 - Sequence index is not an int, slice, or instance with index

Used when a sequence type is indexed with an invalid type. Valid types are ints, slices, and objects with an index method.

invalid-slice-index

E1127 - Slice index is not an int, None, or instance with index

Used when a slice index is not an integer, None, or an object with an index method.

assignment-from-none

E1128 - Assigning result of a function call, where the function returns None

Used when an assignment is done on a function call but the inferred function returns nothing but None.

not-context-manager

E1129 - Context manager '%s' doesn't implement enter and exit.

Used when an instance in a with statement doesn't implement the context manager protocol(enter/exit).

invalid-unary-operand-type

E1130 -

Emitted when a unary operand is used on an object which does not support this type of operation.

unsupported-binary-operation

E1131 -

Emitted when a binary arithmetic operation between two operands is not supported.

repeated-keyword

E1132 - Got multiple values for keyword argument %r in function call

Emitted when a function call got multiple values for a keyword.

not-an-iterable

E1133 - Non-iterable value %s is used in an iterating context

Used when a non-iterable value is used in place where iterable is expected

not-a-mapping

E1134 - Non-mapping value %s is used in a mapping context

Used when a non-mapping value is used in place where mapping is expected

unsupported-membership-test

E1135 - Value '%s' doesn't support membership test

Emitted when an instance in membership test expression doesn't implement membership protocol (contains/iter/getitem).

unsubscriptable-object

E1136 - Value '%s' is unsubscriptable

Emitted when a subscripted value doesn't support subscription (i.e. doesn't define getitem method).

unsupported-assignment-operation

E1137 - %r does not support item assignment

Emitted when an object does not support item assignment (i.e. doesn't define setitem method).

unsupported-delete-operation

E1138 - %r does not support item deletion

Emitted when an object does not support item deletion (i.e. doesn't define delitem method).

invalid-metaclass

E1139 - Invalid metaclass %r used

Emitted whenever we can detect that a class is using, as a metaclass, something which might be invalid for using as a metaclass.

unhashable-dict-key

E1140 - Dict key is unhashable

Emitted when a dict key is not hashable (i.e. doesn't define hash method).

logging-unsupported-format

E1200 - Unsupported logging format character %r (%#02x) at index %d

Used when an unsupported format character is used in a logging statement format string.

logging-format-truncated

E1201 - Logging format string ends in middle of conversion specifier

Used when a logging statement format string terminates before the end of a conversion specifier.

logging-too-many-args

E1205 - Too many arguments for logging format string

Used when a logging format string is given too many arguments.

logging-too-few-args

E1206 - Not enough arguments for logging format string

Used when a logging format string is given too few arguments.

bad-format-character

E1300 - Unsupported format character %r (%#02x) at index %d

Used when an unsupported format character is used in a format string.

truncated-format-string

E1301 - Format string ends in middle of conversion specifier

Used when a format string terminates before the end of a conversion specifier.

mixed-format-string

E1302 - Mixing named and unnamed conversion specifiers in format string

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

format-needs-mapping

E1303 - Expected mapping for format string, not %s

Used when a format string that uses named conversion specifiers is used with an argument that is not a mapping.

missing-format-string-key

E1304 - Missing key %r in format string dictionary

Used when a format string that uses named conversion specifiers is used with a dictionary that doesn't contain all the keys required by the format string.

too-many-format-args

E1305 - Too many arguments for format string

Used when a format string that uses unnamed conversion specifiers is given too many arguments.

too-few-format-args

E1306 - Not enough arguments for format string

Used when a format string that uses unnamed conversion specifiers is given too few arguments

bad-string-format-type

E1307 - Argument %r does not match format type %r

Used when a type required by format string is not suitable for actual argument type

bad-str-strip-call

E1310 - Suspicious argument in %s.%s call

The argument to a str.{l,r,}strip call contains a duplicate character,

invalid-envvar-value

E1507 - %s does not support %s type argument

Env manipulation functions support only string type arguments. See https://docs.python.org/3/library/os.html#os.getenv.

print-statement

E1601 - print statement used

Used when a print statement is used (print is a function in Python 3)

parameter-unpacking

E1602 - Parameter unpacking specified

Used when parameter unpacking is specified for a function(Python 3 doesn't allow it)

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/

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)'.

backtick

E1605 - Use of the `` operator

Used when the deprecated "``" (backtick) operator is used instead of the str() function.

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.

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.

fatal

F0001 -

Used when an error occurred preventing the analysis of a module (unable to find it for instance).

astroid-error

F0002 - %s: %s

Used when an unexpected error occurred while building the Astroid representation. This is usually accompanied by a traceback. Please report such errors !

parse-error

F0010 - error while code parsing: %s

Used when an exception occurred while building the Astroid representation which could be handled by astroid.

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.

raw-checker-failed

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.

bad-inline-option

I0010 - Unable to consider inline option %r

Used when an inline option is either badly formatted or can't be used inside modules.

locally-disabled

I0011 - Locally disabling %s (%s)

Used when an inline option disables a message or a messages category.

file-ignored

I0013 - Ignoring entire file

Used to inform that the file will not be checked

suppressed-message

I0020 - Suppressed %s (from line %d)

A message was triggered on a line, but suppressed explicitly by a disable= comment in the file. This message is not generated for messages that are ignored due to configuration settings.

useless-suppression

I0021 - Useless suppression of %s

Reported when a message is explicitly disabled for a line or a block of code, but never triggered.

deprecated-pragma

I0022 - Pragma "%s" is deprecated, use "%s" instead

Some inline pylint options have been renamed or reworked, only the most recent form should be used. NOTE:skip-all is only available with pylint >= 0.26

use-symbolic-message-instead

I0023 -

Used when a message is enabled or disabled by id.

c-extension-no-member

I1101 - %s %r has no %r member%s, but source is unavailable. Consider adding this module to extension-pkg-whitelist if you want to perform analysis based on run-time introspection of living objects.

Used when a variable is accessed for non-existent member of C extension. Due to unavailability of source static analysis is impossible, but it may be performed by introspecting living objects in run-time.

literal-comparison

R0123 - Comparison to literal

Used when comparing an object to a literal, which is usually what you do not want to do, since you can compare to a different literal than what was expected altogether.

comparison-with-itself

R0124 - Redundant comparison - %s

Used when something is compared against itself.

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.

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.

useless-object-inheritance

R0205 - Class %r inherits from object, can be safely removed from bases in python3

Used when a class inherit from object, which under python3 is implicit, hence can be safely removed from bases.

cyclic-import

R0401 - Cyclic import (%s)

Used when a cyclic import between two or more modules is detected.

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.

too-many-ancestors

R0901 - Too many ancestors (%s/%s)

Used when class has too many parent classes, try to reduce this to get a simpler (and so easier to use) class.

too-many-instance-attributes

R0902 - Too many instance attributes (%s/%s)

Used when class has too many instance attributes, try to reduce this to get a simpler (and so easier to use) class.

too-few-public-methods

R0903 - Too few public methods (%s/%s)

Used when class has too few public methods, so be sure it's really worth it.

too-many-public-methods

R0904 - Too many public methods (%s/%s)

Used when class has too many public methods, try to reduce this to get a simpler (and so easier to use) class.

too-many-return-statements

R0911 - Too many return statements (%s/%s)

Used when a function or method has too many return statement, making it hard to follow.

too-many-branches

R0912 - Too many branches (%s/%s)

Used when a function or method has too many branches, making it hard to follow.

too-many-arguments

R0913 - Too many arguments (%s/%s)

Used when a function or method takes too many arguments.

too-many-locals

R0914 - Too many local variables (%s/%s)

Used when a function or method has too many local variables.

too-many-statements

R0915 - Too many statements (%s/%s)

Used when a function or method has too many statements. You should then split it in smaller functions / methods.

too-many-boolean-expressions

R0916 - Too many boolean expressions in if statement (%s/%s)

Used when an if statement contains too many boolean expressions.

consider-merging-isinstance

R1701 - Consider merging these isinstance calls to isinstance(%s, (%s))

Used when multiple consecutive isinstance calls can be merged into one.

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.

simplifiable-if-statement

R1703 - The if statement can be replaced with %s

Used when an if statement can be replaced with 'bool(test)'.

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.

no-else-return

R1705 - Unnecessary "%s" after "return"

Used in order to highlight an unnecessary block of code following an if containing a return statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a return statement.

consider-using-ternary

R1706 - Consider using ternary (%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.

stop-iteration-return

R1708 - Do not raise StopIteration in generator, use return statement instead

According to PEP479, the raise of StopIteration to end the loop of a generator may lead to hard to find bugs. This PEP specify that raise StopIteration has to be replaced by a simple return statement

simplify-boolean-expression

R1709 - Boolean expression may be simplified to %s

Emitted when redundant pre-python 2.5 ternary syntax is used.

inconsistent-return-statements

R1710 - Either all return statements in a function should return an expression, or none of them should.

According to PEP8, if any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable)

useless-return

R1711 - Useless return at end of function or method

Emitted when a single "return" or "return None" statement is found at the end of function or method definition. This statement can safely be removed because Python will implicitly return None

consider-swap-variables

R1712 - Consider using tuple unpacking for swapping variables

You do not have to use a temporary variable in order to swap variables. Using "tuple unpacking" to directly swap variables makes the intention more clear.

consider-using-join

R1713 - Consider using str.join(sequence) for concatenating strings from an iterable

Using str.join(sequence) is faster, uses less memory and increases readability compared to for-loop iteration.

consider-using-in

R1714 - Consider merging these comparisons with "in" to %r

To check if a variable is equal to one of many values,combine the values into a tuple and check if the variable is contained "in" it instead of checking for equality against each of the values.This is faster and less verbose.

consider-using-get

R1715 - Consider using dict.get for getting values from a dict if a key is present or a default if not

Using the builtin dict.get for getting a value from a dictionary if a key is present or a default if not, is simpler and considered more idiomatic, although sometimes a bit slower

chained-comparison

R1716 - Simplify chained comparison between the operands

This message is emitted when pylint encounters boolean operation like"a < b and b < c", suggesting instead to refactor it to "a < b < c"

consider-using-dict-comprehension

R1717 - Consider using a dictionary comprehension

Although there is nothing syntactically wrong with this code, it is hard to read and can be simplified to a dict comprehension.Also it is faster since you don't need to create another transient list

consider-using-set-comprehension

R1718 - Consider using a set comprehension

Although there is nothing syntactically wrong with this code, it is hard to read and can be simplified to a set comprehension.Also it is faster since you don't need to create another transient list

simplifiable-if-expression

R1719 - The if expression can be replaced with %s

Used when an if expression can be replaced with 'bool(test)'.

unreachable

W0101 - Unreachable code

Used when there is some code behind a "return" or "raise" statement, which will never be accessed.

dangerous-default-value

W0102 - Dangerous default value %s as argument

Used when a mutable value as list or dictionary is detected in a default value for an argument.

pointless-statement

W0104 - Statement seems to have no effect

Used when a statement doesn't have (or at least seems to) any effect.

pointless-string-statement

W0105 - String statement has no effect

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

expression-not-assigned

W0106 - Expression "%s" is assigned to nothing

Used when an expression that is not a function call is assigned to nothing. Probably something else was intended.

unnecessary-pass

W0107 - Unnecessary pass statement

Used when a "pass" statement that can be avoided is encountered.

unnecessary-lambda

W0108 - Lambda may not be necessary

Used when the body of a lambda expression is a function call on the same argument list as the lambda itself; such lambda expressions are in all but a few cases replaceable with the function being called in the body of the lambda.

duplicate-key

W0109 - Duplicate key %r in dictionary

Used when a dictionary expression binds the same key multiple times.

assign-to-new-keyword

W0111 - Name %s will become a keyword in Python %s

Used when assignment will become invalid in future Python release due to introducing new keyword.

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.

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 !

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.

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.

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.

comparison-with-callable

W0143 - Comparing against a callable, did you omit the parenthesis?

This message is emitted when pylint detects that a comparison with a callable was made, which might suggest that some parenthesis were omitted, resulting in potential unwanted behaviour.

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.

attribute-defined-outside-init

W0201 - Attribute %r defined outside init

Used when an instance attribute is defined outside the init method.

bad-staticmethod-argument

W0211 - Static method with %r as first argument

Used when a static method has "self" or a value specified in valid- classmethod-first-arg option or valid-metaclass-classmethod-first-arg option as first argument.

protected-access

W0212 - Access to a protected member %s of a client class

Used when a protected member (i.e. class member with a name beginning with an underscore) is access outside the class or a descendant of the class where it's defined.

arguments-differ

W0221 - 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.

abstract-method

W0223 - Method %r is abstract in class %r but is not overridden

Used when an abstract method (i.e. raise NotImplementedError) is not overridden in concrete class.

super-init-not-called

W0231 - init method from base class %r is not called

Used when an ancestor class method has an init method which is not called by a derived class.

no-init

W0232 - Class has no init method

Used when a class has no init method, neither its parent classes.

non-parent-init-called

W0233 - init method from a non direct base class %r is called

Used when an init method is called on a class which is not in the direct ancestors for the analysed class.

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.

unnecessary-semicolon

W0301 - Unnecessary semicolon

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

bad-indentation

W0311 - Bad indentation. Found %s %s, expected %s

Used when an unexpected number of indentation's tabulations or spaces has been found.

mixed-indentation

W0312 - Found indentation with %ss instead of %ss

Used when there are some mixed tabs and spaces in a module.

wildcard-import

W0401 - Wildcard import %s

Used when from module import * is detected.

deprecated-module

W0402 - Uses of a deprecated module %r

Used a module marked as deprecated is imported.

reimported

W0404 - Reimport %r (imported line %s)

Used when a module is reimported multiple times.

import-self

W0406 - Module import itself

Used when a module is importing itself.

misplaced-future

W0410 - future import is not the first non docstring statement

Python 2.5 and greater require future import to be the first non docstring statement in the module.

fixme

W0511 -

Used when a warning note as FIXME or XXX is detected.

global-variable-undefined

W0601 - Global variable %r undefined at the module level

Used when a variable is defined through the "global" statement but the variable is not defined in the module scope.

global-variable-not-assigned

W0602 - Using global for %r but no assignment is done

Used when a variable is defined through the "global" statement but no assignment to this variable is done.

global-statement

W0603 - Using the global statement

Used when you use the "global" statement to update a global variable. Pylint just try to discourage this usage. That doesn't mean you 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

unused-import

W0611 - Unused %s

Used when an imported module or variable is not used.

unused-variable

W0612 - Unused variable %r

Used when a variable is defined but not used.

unused-argument

W0613 - Unused argument %r

Used when a function or method argument is not used.

unused-wildcard-import

W0614 - Unused import %s from wildcard import

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

redefined-outer-name

W0621 - Redefining name %r from outer scope (line %s)

Used when a variable's name hides a name defined in the outer scope.

redefined-builtin

W0622 - Redefining built-in %r

Used when a variable or function override a built-in.

redefine-in-handler

W0623 - Redefining name %r from %s in exception handler

Used when an exception handler assigns the exception to an existing name

undefined-loop-variable

W0631 - Using possibly undefined loop variable %r

Used when a loop variable (i.e. defined by a for loop or a list comprehension or a generator expression) is used outside the loop.

unbalanced-tuple-unpacking

W0632 - Possible unbalanced tuple unpacking with sequence%s: left side has %d label(s), right side has %d value(s)

Used when there is an unbalanced tuple unpacking in assignment

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.

possibly-unused-variable

W0641 - Possibly unused variable %r

Used when a variable is defined but might not be used. The possibility comes from the fact that locals() might be used, which could consume or not the said variable

self-cls-assignment

W0642 - Invalid assignment to %s in method

Invalid assignment to self or cls in instance or class method respectively.

bare-except

W0702 - No exception type(s) specified

Used when an except clause doesn't specify exceptions type to catch.

broad-except

W0703 - Catching too general exception %s

Used when an except catches a too general exception, possibly burying unrelated errors.

duplicate-except

W0705 - Catching previously caught exception type %s

Used when an except catches a type that was already caught by a previous handler.

try-except-raise

W0706 - The except handler raises immediately

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

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):"

raising-format-tuple

W0715 - Exception arguments suggest string formatting might be intended

Used when passing multiple arguments to an exception constructor, the first of them a string literal containing what appears to be placeholders intended for formatting

keyword-arg-before-vararg

W1113 - Keyword argument before variable positional arguments list in the definition of %s function

When defining a keyword argument before variable positional arguments, one can end up in having multiple values passed for the aforementioned parameter in case the method is called with keyword arguments.

logging-not-lazy

W1201 - Specify string format arguments as logging function parameters

Used when a logging statement has a call form of "logging.(format_string % (format_args...))". Such calls should leave string interpolation to the logging method itself and be written "logging.(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.(format_string.format(format_args...))". Such calls should use % formatting instead, but leave interpolation to the logging function by passing the parameters as arguments.

logging-fstring-interpolation

W1203 - Use % formatting in logging functions and pass the % parameters as arguments

Used when a logging statement has a call form of "logging.method(f"..."))". Such calls should use % formatting instead, but leave interpolation to the logging function by passing the parameters as arguments.

bad-format-string-key

W1300 - Format string dictionary key should be a string, not %s

Used when a format string that uses named conversion specifiers is used with a dictionary whose keys are not all strings.

unused-format-string-key

W1301 - Unused key %r in format string dictionary

Used when a format string that uses named conversion specifiers is used with a dictionary that contains keys not required by the format string.

bad-format-string

W1302 - Invalid format string

Used when a PEP 3101 format string is invalid.

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.

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.

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}').

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.

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.

duplicate-string-formatting-argument

W1308 - Duplicate string formatting argument %r, consider passing as named argument

Used when we detect that a string formatting is repeating an argument instead of using named string arguments

anomalous-backslash-in-string

W1401 - Anomalous backslash in string: '%s'. String constant might be missing an r prefix.

Used when a backslash is in a literal string but not as an escape.

anomalous-unicode-escape-in-string

W1402 - Anomalous Unicode escape in byte string: '%s'. String constant might be missing an r or u prefix.

Used when an escape like \u is encountered in a byte string where it has no effect.

implicit-str-concat-in-sequence

W1403 - Implicit string concatenation found in %s

String literals are implicitly concatenated in a literal iterable definition : maybe a comma is missing ?

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.

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.

bad-thread-instantiation

W1506 - threading.Thread needs the target function

The warning is emitted when a threading.Thread class is instantiated without the target function being passed. By default, the first parameter is the group param, not the target param.

shallow-copy-environ

W1507 - Using copy.copy(os.environ). Use os.environ.copy() instead.

os.environ is not a dict object but proxy object, so shallow copy has still effects on original object. See https://bugs.python.org/issue15373 for reference.

invalid-envvar-default

W1508 - %s default type is %s. Expected str or None.

Env manipulation functions return None or str values. Supplying anything different as a default may cause bugs. See https://docs.python.org/3/library/os.html#os.getenv.

subprocess-popen-preexec-fn

W1509 - Using preexec_fn keyword which may be unsafe in the presence of threads

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

apply-builtin

W1601 - apply built-in referenced

Used when the apply built-in function is referenced (missing from Python 3)

basestring-builtin

W1602 - basestring built-in referenced

Used when the basestring built-in function is referenced (missing from Python 3)

buffer-builtin

W1603 - buffer built-in referenced

Used when the buffer built-in function is referenced (missing from Python 3)

cmp-builtin

W1604 - cmp built-in referenced

Used when the cmp built-in function is referenced (missing from Python 3)

coerce-builtin

W1605 - coerce built-in referenced

Used when the coerce built-in function is referenced (missing from Python 3)

execfile-builtin

W1606 - execfile built-in referenced

Used when the execfile built-in function is referenced (missing from Python 3)

file-builtin

W1607 - file built-in referenced

Used when the file built-in function is referenced (missing from Python 3)

long-builtin

W1608 - long built-in referenced

Used when the long built-in function is referenced (missing from Python 3)

raw_input-builtin

W1609 - raw_input built-in referenced

Used when the raw_input built-in function is referenced (missing from Python 3)

reduce-builtin

W1610 - reduce built-in referenced

Used when the reduce built-in function is referenced (missing from Python 3)

standarderror-builtin

W1611 - StandardError built-in referenced

Used when the StandardError built-in function is referenced (missing from Python 3)

unicode-builtin

W1612 - unicode built-in referenced

Used when the unicode built-in function is referenced (missing from Python 3)

xrange-builtin

W1613 - xrange built-in referenced

Used when the xrange built-in function is referenced (missing from Python 3)

coerce-method

W1614 - coerce method defined

Used when a coerce method is defined (method is not used by Python 3)

delslice-method

W1615 - delslice method defined

Used when a delslice method is defined (method is not used by Python 3)

getslice-method

W1616 - getslice method defined

Used when a getslice method is defined (method is not used by Python 3)

setslice-method

W1617 - setslice method defined

Used when a setslice method is defined (method is not used by Python 3)

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)

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)

dict-iter-method

W1620 - Calling a dict.iter*() method

Used for calls to dict.iterkeys(), itervalues() or iteritems() (Python 3 lacks these methods)

dict-view-method

W1621 - Calling a dict.view*() method

Used for calls to dict.viewkeys(), viewvalues() or viewitems() (Python 3 lacks these methods)

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)

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)

indexing-exception

W1624 - Indexing exceptions will not work on Python 3

Indexing exceptions will not work on Python 3. Use exception.args[index] instead.

raising-string

W1625 - Raising a string exception

Used when a string exception is raised. This will not work on Python 3.

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.

oct-method

W1627 - oct method defined

Used when an oct method is defined (method is not used by Python 3)

hex-method

W1628 - hex method defined

Used when a hex method is defined (method is not used by Python 3)

nonzero-method

W1629 - nonzero method defined

Used when a nonzero method is defined (method is not used by Python 3)

cmp-method

W1630 - cmp method defined

Used when a cmp method is defined (method is not used by Python 3)

input-builtin

W1632 - input built-in referenced

Used when the input built-in is referenced (backwards-incompatible semantics in Python 3)

round-builtin

W1633 - round built-in referenced

Used when the round built-in is referenced (backwards-incompatible semantics in Python 3)

intern-builtin

W1634 - intern built-in referenced

Used when the intern built-in is referenced (Moved to sys.intern in Python 3)

unichr-builtin

W1635 - unichr built-in referenced

Used when the unichr built-in is referenced (Use chr in Python 3)

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)

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)

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)

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)

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.

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.

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)

idiv-method

W1643 - idiv method defined

Used when an idiv method is defined. Using __itruediv__ and setting__idiv__ = itruediv should be preferred.(method is not used by Python 3)

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)

exception-message-attribute

W1645 - Exception.message removed in Python 3

Used when the message attribute is accessed on an Exception. Use str(exception) instead.

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.

sys-max-int

W1647 - sys.maxint removed in Python 3

Used when accessing sys.maxint. Use sys.maxsize instead.

bad-python3-import

W1648 - Module moved in Python 3

Used when importing a module that no longer exists in Python 3.

deprecated-string-function

W1649 - Accessing a deprecated function on the string module

Used when accessing a string function that has been deprecated in Python 3.

deprecated-str-translate-call

W1650 - Using str.translate with deprecated deletechars parameters

Used when using the deprecated deletechars parameters from str.translate. Use re.sub to remove the desired characters

deprecated-itertools-function

W1651 - Accessing a deprecated function on the itertools module

Used when accessing a function on itertools that has been removed in Python 3.

deprecated-types-field

W1652 - Accessing a deprecated fields on the types module

Used when accessing a field on types that has been removed in Python 3.

next-method-defined

W1653 - next method defined

Used when a next method is defined that would be an iterator in Python 2 but is treated as a normal function in Python 3.

dict-items-not-iterating

W1654 - dict.items referenced when not iterating

Used when dict.items is referenced in a non-iterating context (returns an iterator in Python 3)

dict-keys-not-iterating

W1655 - dict.keys referenced when not iterating

Used when dict.keys is referenced in a non-iterating context (returns an iterator in Python 3)

dict-values-not-iterating

W1656 - dict.values referenced when not iterating

Used when dict.values is referenced in a non-iterating context (returns an iterator in Python 3)

deprecated-operator-function

W1657 - Accessing a removed attribute on the operator module

Used when accessing a field on operator module that has been removed in Python 3.

deprecated-urllib-function

W1658 - Accessing a removed attribute on the urllib module

Used when accessing a field on urllib module that has been removed or moved in Python 3.

xreadlines-attribute

W1659 - Accessing a removed xreadlines attribute

Used when accessing the xreadlines() function on a file stream, removed in Python 3.

deprecated-sys-function

W1660 - Accessing a removed attribute on the sys module

Used when accessing a field on sys module that has been removed in Python 3.

exception-escape

W1661 - Using an exception object that was bound by an except handler

Emitted when using an exception, that was bound in an except handler, outside of the except handler. On Python 3 these exceptions will be deleted once they get out of the except handler.

comprehension-escape

W1662 - Using a variable that was bound inside a comprehension

Emitted when using a variable, that was bound in a comprehension handler, outside of the comprehension itself. On Python 3 these variables will be deleted outside of the comprehension.

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