Source code for wemake_python_styleguide.violations.consistency

These checks limit the Python's inconsistency.

We can do the same things differently in Python.
For example, there are three ways to format a string.
There are several ways to write the same number.

We like our code to be consistent.
It is easier to bare with your code base if you follow these rules.

So, we choose a single way to do things.
It does not mean that we choose the best way to do it.
But, we value consistency more than being 100% right.
And we are ready to suffer all trade-offs that might come.

Once again, these rules are highly subjective. But, we love them.

.. currentmodule:: wemake_python_styleguide.violations.consistency


.. autosummary::


Consistency checks

.. autoclass:: LocalFolderImportViolation
.. autoclass:: DottedRawImportViolation
.. autoclass:: UnicodeStringViolation
.. autoclass:: UnderscoredNumberViolation
.. autoclass:: PartialFloatViolation
.. autoclass:: FormattedStringViolation
.. autoclass:: RequiredBaseClassViolation
.. autoclass:: MultipleIfsInComprehensionViolation
.. autoclass:: ConstantCompareViolation
.. autoclass:: CompareOrderViolation
.. autoclass:: BadNumberSuffixViolation
.. autoclass:: MultipleInCompareViolation
.. autoclass:: UselessCompareViolation
.. autoclass:: MissingSpaceBetweenKeywordAndParenViolation
.. autoclass:: ConstantConditionViolation
.. autoclass:: ObjectInBaseClassesListViolation
.. autoclass:: MultipleContextManagerAssignmentsViolation
.. autoclass:: ParametersIndentationViolation
.. autoclass:: ExtraIndentationViolation
.. autoclass:: WrongBracketPositionViolation
.. autoclass:: MultilineFunctionAnnotationViolation
.. autoclass:: UppercaseStringModifierViolation
.. autoclass:: WrongMultilineStringViolation
.. autoclass:: ModuloStringFormatViolation
.. autoclass:: InconsistentReturnViolation
.. autoclass:: InconsistentYieldViolation
.. autoclass:: ImplicitStringConcatenationViolation
.. autoclass:: UselessContinueViolation
.. autoclass:: UselessNodeViolation
.. autoclass:: UselessExceptCaseViolation
.. autoclass:: UselessOperatorsViolation
.. autoclass:: InconsistentReturnVariableViolation
.. autoclass:: WalrusViolation
.. autoclass:: ImplicitComplexCompareViolation
.. autoclass:: ReversedComplexCompareViolation
.. autoclass:: WrongLoopIterTypeViolation
.. autoclass:: ExplicitStringConcatViolation
.. autoclass:: MultilineConditionsViolation
.. autoclass:: WrongMethodOrderViolation
.. autoclass:: NumberWithMeaninglessZeroViolation
.. autoclass:: PositiveExponentViolation
.. autoclass:: WrongHexNumberCaseViolation
.. autoclass:: ImplicitRawStringViolation
.. autoclass:: BadComplexNumberSuffixViolation
.. autoclass:: ZeroDivisionViolation
.. autoclass:: MeaninglessNumberOperationViolation
.. autoclass:: OperationSignNegationViolation
.. autoclass:: VagueImportViolation
.. autoclass:: LineStartsWithDotViolation
.. autoclass:: RedundantSubscriptViolation
.. autoclass:: AugmentedAssignPatternViolation
.. autoclass:: UnnecessaryLiteralsViolation
.. autoclass:: MultilineLoopViolation
.. autoclass:: IncorrectYieldFromTargetViolation
.. autoclass:: ConsecutiveYieldsViolation
.. autoclass:: BracketBlankLineViolation
.. autoclass:: IterableUnpackingViolation
.. autoclass:: LineCompriseCarriageReturnViolation
.. autoclass:: FloatZeroViolation


from typing_extensions import final

from wemake_python_styleguide.violations.base import (

[docs]@final class LocalFolderImportViolation(ASTViolation): """ Forbids to have imports relative to the current folder. Reasoning: We should pick one style and stick to it. We have decided to use the explicit one. Solution: Refactor your imports to use the absolute path. Example:: # Correct: from my_package.version import get_version # Wrong: from .version import get_version from ..drivers import MySQLDriver .. versionadded:: 0.1.0 """ error_template = 'Found local folder import' code = 300
[docs]@final class DottedRawImportViolation(ASTViolation): """ Forbids to use imports like ``import os.path``. Reasoning: There too many different ways to import something. We should pick one style and stick to it. We have decided to use the readable one. Solution: Refactor your import statement. Example:: # Correct: from os import path # Wrong: import os.path .. versionadded:: 0.1.0 """ error_template = 'Found dotted raw import: {0}' code = 301
[docs]@final class UnicodeStringViolation(TokenizeViolation): """ Forbids to use ``u`` string prefix. Reasoning: We do not need this prefix since ``python2``. But, it is still possible to find it inside the codebase. Solution: Remove this prefix. Example:: # Correct: nickname = 'sobolevn' file_contents = b'aabbcc' # Wrong: nickname = u'sobolevn' .. versionadded:: 0.1.0 """ code = 302 error_template = 'Found unicode string prefix: {0}'
[docs]@final class UnderscoredNumberViolation(TokenizeViolation): """ Forbids to use underscores (``_``) in numbers. Reasoning: It is possible to write ``1000`` in three different ways: ``1_000``, ``10_00``, and ``100_0``. And it would be still the same number. Count how many ways there are to write bigger numbers. Currently, it all depends on the cultural habits of the author. We enforce a single way to write numbers: without the underscore. Solution: Numbers should be written as numbers: ``1000``. If you have a very big number with a lot of zeros, use multiplication. Example:: # Correct: phone = 88313443 million = 1000000 # Wrong: phone = 8_83_134_43 million = 100_00_00 .. versionadded:: 0.1.0 """ code = 303 error_template = 'Found underscored number: {0}'
[docs]@final class PartialFloatViolation(TokenizeViolation): """ Forbids to use partial floats like ``.05`` or ``23.``. Reasoning: Partial numbers are hard to read and they can be confused with other numbers. For example, it is really easy to confuse ``0.5`` and ``.05`` when reading through the source code. Solution: Use full versions with leading and starting zeros. Example:: # Correct: half = 0.5 ten_float = 10.0 # Wrong: half = .5 ten_float = 10. .. versionadded:: 0.1.0 """ code = 304 error_template = 'Found partial float: {0}'
[docs]@final class FormattedStringViolation(ASTViolation): """ Forbids to use ``f`` strings. Reasoning: ``f`` strings loses context too often and they are hard to lint. Imagine that you have a string that breaks when you move it two lines above. That's not how a string should behave. Also, they promote a bad practice: putting your logic inside the template. Solution: Use ``.format()`` with indexed params instead. See also: Example:: # Wrong: f'Result is: {2 + 2}' # Correct: 'Result is: {0}'.format(2 + 2) 'Hey {user}! How are you?'.format(user='sobolevn') .. versionadded:: 0.1.0 """ error_template = 'Found `f` string' code = 305
[docs]@final class RequiredBaseClassViolation(ASTViolation): """ Forbids to write classes without base classes. Please, note that this rule has nothing to do with ``python2``. We care only about consistency here. Reasoning: We just need to decide how to do it. We need a single and unified rule about base classes. We have decided to stick to the explicit base class notation. Why? Because it is consistent with other use-cases. When we have a base class ``A``, we write ``class MyClass(A):``. When we have no base class, we have an implicit ``object`` base class. So, we still use the same syntax: ``class MyClass(object):``. Solution: Add a base class. Example:: # Correct: class Some(object): ... # Wrong: class Some: ... .. versionadded:: 0.1.0 """ error_template = 'Found class without a base class: {0}' code = 306
[docs]@final class MultipleIfsInComprehensionViolation(ASTViolation): """ Forbids to have multiple ``if`` statements inside list comprehensions. Reasoning: It is very hard to read multiple ``if`` statements inside a list comprehension. Since it is even hard to tell all of them should pass or fail. Solution: Use a single ``if`` statement inside list comprehensions. Use ``filter()`` if you have complicated logic. Example:: # Wrong: nodes = [node for node in html if node != 'b' if node != 'i'] # Correct: nodes = [node for node in html if node not in ('b', 'i')] .. versionadded:: 0.1.0 """ error_template = 'Found list comprehension with multiple `if`s' code = 307
[docs]@final class ConstantCompareViolation(ASTViolation): """ Forbids to have compares between two literals. Reasoning: When two constants are compared it is typically an indication of a mistake, since the Boolean value of the compare, will always be the same. Solution: Remove the constant compare and any associated dead code. Example:: # Wrong: if 60 * 60 < 1000: do_something() else: do_something_else() # Correct: do_something_else() .. versionadded:: 0.3.0 """ error_template = 'Found constant compare' code = 308
[docs]@final class CompareOrderViolation(ASTViolation): """ Forbids comparison where argument doesn't come first. Reasoning: It is hard to read the code when you have to shuffle ordering of the arguments all the time. Bring consistency to the compare! Solution: Refactor your compare expression, place the argument first. Example:: # Correct: if some_x > 3: if 3 < some_x < 10: # Wrong: if 3 < some_x: .. versionadded:: 0.3.0 """ error_template = 'Found reversed compare order' code = 309
[docs]@final class BadNumberSuffixViolation(TokenizeViolation): """ Forbids to use capital ``X``, ``O``, ``B``, and ``E`` in numbers. Reasoning: Octal, hex, binary and scientific notation suffixes could be written in two possible notations: lowercase and uppercase. Which brings confusion and decreases code consistency and readability. We enforce a single way to write numbers with suffixes: suffix with lowercase chars. Solution: Octal, hex, binary and scientific notation suffixes in numbers should be written in lowercase. Example:: # Correct: hex_number = 0xFF octal_number = 0o11 binary_number = 0b1001 number_with_scientific_notation = 1.5e+10 # Wrong: hex_number = 0XFF octal_number = 0O11 binary_number = 0B1001 number_with_scientific_notation = 1.5E+10 .. versionadded:: 0.3.0 """ error_template = 'Found bad number suffix: {0}' code = 310
[docs]@final class MultipleInCompareViolation(ASTViolation): """ Forbids comparison where multiple ``in`` checks. Reasoning: Using multiple ``in`` is unreadable. Solution: Refactor your compare expression to use several ``and`` conditions or separate ``if`` statements in case it is appropriate. Example:: # Correct: if item in bucket and bucket in master_list_of_buckets: if x_coord not in line and line not in square: # Wrong: if item in bucket in master_list_of_buckets: if x_cord not in line not in square: .. versionadded:: 0.3.0 .. versionchanged:: 0.10.0 """ error_template = 'Found multiple `in` compares' code = 311
[docs]@final class UselessCompareViolation(ASTViolation): """ Forbids to have compares between the same variable. Reasoning: When the same variables are compared it is typically an indication of a mistake, since the Boolean value of the compare will always be the same. Solution: Remove the same variable compare and any associated dead code. Example:: # Correct: do_something() # Wrong: if a < a: do_something() else: do_something_else() .. versionadded:: 0.3.0 """ error_template = 'Found compare between same variable' code = 312
[docs]@final class MissingSpaceBetweenKeywordAndParenViolation(TokenizeViolation): """ Enforces to separate parenthesis from the keywords with spaces. Reasoning: Some people use ``return`` and ``yield`` keywords as functions. The same happened to good old ``print`` in Python2. Solution: Insert space symbol between keyword and open paren. Example:: # Wrong: def func(): a = 1 b = 2 del(a, b) yield(1, 2, 3) # Correct: def func(): a = 1 del (a, b) yield (1, 2, 3) .. versionadded:: 0.3.0 """ error_template = 'Found parens right after a keyword' code = 313
[docs]@final class ConstantConditionViolation(ASTViolation): """ Forbids using ``if`` statements that use invalid conditionals. Reasoning: When invalid conditional arguments are used it is typically an indication of a mistake, since the value of the conditional result will always be the same. Solution: Remove the conditional and any associated dead code. Example:: # Correct: if value is True: ... # Wrong: if True: ... .. versionadded:: 0.3.0 """ error_template = 'Found conditional that always evaluates to same result' code = 314
[docs]@final class ObjectInBaseClassesListViolation(ASTViolation): """ Forbids extra ``object`` in parent classes list. Reasoning: We should allow object only when we explicitly use it as a single parent class. When there is another class or there are multiple parents - we should not allow it for the consistency reasons. Solution: Remove extra ``object`` parent class from the list. Example:: # Correct: class SomeClassName(object): ... class SomeClassName(FirstParentClass, SecondParentClass): ... # Wrong: class SomeClassName(FirstParentClass, SecondParentClass, object): ... .. versionadded:: 0.3.0 """ error_template = 'Found extra `object` in parent classes list' code = 315
[docs]@final class MultipleContextManagerAssignmentsViolation(ASTViolation): """ Forbids multiple assignment targets for context managers. Reasoning: It is hard to distinguish whether ``as`` should unpack into tuple or we are just using two context managers. Solution: Use several context managers. Or explicit brackets. Example:: # Correct: with open('') as first: with second: ... with some_context as (first, second): ... # Wrong: with open('') as first, second: ... .. versionadded:: 0.6.0 """ error_template = 'Found context manager with too many assignments' code = 316
[docs]@final class ParametersIndentationViolation(ASTViolation): """ Forbids to use incorrect parameters indentation. Reasoning: It is really easy to spoil your perfect, readable code with incorrect multi-line parameters indentation. Since it is really easy to style them in any of 100 possible ways. We enforce a strict rule about how it is possible to write these multi-line parameters. Solution: Use consistent multi-line parameters indentation. Example:: # Correct: def my_function(arg1, arg2, arg3) -> None: return None print(1, 2, 3, 4, 5, 6) def my_function( arg1, arg2, arg3, ) -> None: return None print( 1, 2, 3, 4, 5, 6, ) def my_function( arg1, arg2, arg3, ) -> None: return None print( first_variable, 2, third_value, 4, 5, last_item, ) # Special case: print('some text', 'description', [ first_variable, second_variable, third_variable, last_item, ], end='') # Correct complex case: @pytest.mark.parametrize(('boolean_arg', 'string_arg'), [ (True, "string"), (False, "another string"), ]) Everything else is considered a violation. This rule checks: lists, sets, tuples, dicts, calls, functions, methods, and classes. .. versionadded:: 0.6.0 """ error_template = 'Found incorrect multi-line parameters' code = 317
[docs]@final class ExtraIndentationViolation(TokenizeViolation): """ Forbids to use extra indentation. Reasoning: You can use extra indentation for lines of code. Python allows you to do that in case you will keep the indentation level equal for this specific node. But, that's insane! Solution: We should stick to 4 spaces for an indentation block. Each next block should be indented by just 4 extra spaces. Example:: # Correct: def test(): print('test') # Wrong: def test(): print('test') This rule is consistent with the "Vertical Hanging Indent" option for ``multi_line_output`` setting of ``isort``. To avoid conflicting rules, you should set ``multi_line_output = 3`` in the ``isort`` settings. See also: .. versionadded:: 0.6.0 """ error_template = 'Found extra indentation' code = 318
[docs]@final class WrongBracketPositionViolation(TokenizeViolation): """ Forbids to have brackets in the wrong position. Reasoning: You can do bizzare things with bracket positioning in python. We require all brackets to be consistent. Solution: Place bracket on the same line, in case of a single line expression. Or place the bracket on a new line in case of a multi-line expression. Example:: # Correct: print([ 1, 2, 3, ]) print( 1, 2, ) def _annotate_brackets( tokens: List[tokenize.TokenInfo], ) -> TokenLines: ... # Wrong: print([ 1, 2, 3], ) print( 1, 2) def _annotate_brackets( tokens: List[tokenize.TokenInfo]) -> TokenLines: ... We check round, square, and curly brackets. .. versionadded:: 0.6.0 """ error_template = 'Found bracket in wrong position' code = 319
[docs]@final class MultilineFunctionAnnotationViolation(ASTViolation): """ Forbids to use multi-line function type annotations. Reasoning: Functions with multi-line type annotations are unreadable. Solution: Use type annotations that fit into a single line to annotate functions. If your annotation is too long, then use type aliases. Example:: # Correct: def create_list(length: int) -> List[int]: ... # Wrong: def create_list(length: int) -> List[ int, ]: ... This rule checks argument and return type annotations. .. versionadded:: 0.6.0 """ error_template = 'Found multi-line function type annotation' code = 320
[docs]@final class UppercaseStringModifierViolation(TokenizeViolation): """ Forbids to use uppercase string modifiers. Reasoning: String modifiers should be consistent. Solution: Use lowercase modifiers. Example:: # Correct: some_string = r'/regex/' some_bytes = b'123' # Wrong: some_string = R'/regex/' some_bytes = B'123' .. versionadded:: 0.6.0 """ error_template = 'Found uppercase string modifier: {0}' code = 321
[docs]@final class WrongMultilineStringViolation(TokenizeViolation): ''' Forbids to use triple quotes for singleline strings. Reasoning: String quotes should be consistent. Solution: Use single quotes for single-line strings. Triple quotes are only allowed for real multiline strings. Example:: # Correct: single_line = 'abc' multiline = """ one two """ # Wrong: some_string = """abc""" some_bytes = b"""123""" Docstrings are ignored from this rule. You must use triple quotes strings for docstrings. .. versionadded:: 0.7.0 ''' error_template = 'Found incorrect multi-line string' code = 322
[docs]@final class ModuloStringFormatViolation(ASTViolation): """ Forbids to use ``%`` formatting on strings. We check for string formatting. We try not to issue false positives. It is better for us to ignore a real (but hard to detect) case, then marking a valid one as incorrect. Internally we check for this pattern in string definitions:: %[(name)] [flags] [width] [.precision] [{h | l}] type This is a ``C`` format specification. Related to :class:`~FormattedStringViolation` and solves the same problem. Reasoning: You must use a single formatting method across your project. Solution: We enforce to use string ``.format()`` method for this task. Example:: # Correct: 'some string', 'your name: {0}', 'data: {data}' # Wrong: 'my name is: %s', 'data: %(data)d' See also: .. versionadded:: 0.14.0 """ error_template = 'Found `%` string formatting' code = 323
[docs]@final class InconsistentReturnViolation(ASTViolation): """ Enforces to have consistent ``return`` statements. Rules are: 1. if any ``return`` has a value, all ``return`` nodes should have a value 2. do not place ``return`` without value at the end of a function This rule respects ``mypy`` style of placing ``return`` statements. There should be no conflict with these two checks. Reasoning: This is done for pure consistency and readability of your code. Eventually, this rule may also find some bugs in your code. Solution: Add or remove values from the ``return`` statements to make them consistent. Remove ``return`` statement from the function end. Example:: # Correct: def function(): if some: return 2 return 1 # Wrong: def function(): if some: return return 1 .. versionadded:: 0.7.0 """ error_template = 'Found inconsistent `return` statement' code = 324
[docs]@final class InconsistentYieldViolation(ASTViolation): """ Enforces to have consistent ``yield`` statements. Rules are: 1. if any ``yield`` has a value, all ``yield`` nodes should have a value This rule respects ``mypy`` style of placing ``yield`` statements. There should be no conflict with these two checks. Reasoning: This is done for pure consistency and readability of your code. Eventually, this rule may also find some bugs in your code. Solution: Add or remove values from the ``yield`` statements to make them consistent. Example:: # Correct: def function(): if some: yield 2 yield 1 # Wrong: def function(): if some: yield yield 1 .. versionadded:: 0.7.0 """ error_template = 'Found inconsistent `yield` statement' code = 325
[docs]@final class ImplicitStringConcatenationViolation(TokenizeViolation): """ Forbids to use implicit string concatenation. Reasoning: This is error-prone, since you can possibly miss a comma in a collection of string and get an implicit concatenation. And because there are different and safe ways to do the same thing it is better to use them instead. Solution: Use ``+`` or ``.format()`` to join strings. Example:: # Correct: text = 'first' + 'second' # Wrong: text = 'first' 'second' .. versionadded:: 0.7.0 """ error_template = 'Found implicit string concatenation' code = 326
[docs]@final class UselessContinueViolation(ASTViolation): """ Forbids to use meaningless ``continue`` node in loops. Reasoning: Placing this keyword in the end of any loop won't make any difference to your code. And we prefer not to have meaningless constructs in our code. Solution: Remove useless ``continue`` node from the loop. Example:: # Correct: for number in [1, 2, 3]: if number < 2: continue print(number) for number in [1, 2, 3]: with suppress(Exception): do_smth(some_obj) # Wrong: for number in [1, 2, 3]: print(number) continue for number in [1, 2, 3]: try: do_smth(some_obj) except Exception: continue .. versionadded:: 0.7.0 """ error_template = 'Found useless `continue` at the end of the loop' code = 327
[docs]@final class UselessNodeViolation(ASTViolation): """ Forbids to use meaningless nodes. Reasoning: Some nodes might be completely useless. They will literally do nothing. Sometimes they are hard to find, because this situation can be caused by a recent refactoring or just by acedent. This might be also an overuse of syntax. Solution: Remove node or make sure it makes sense. Example:: # Wrong: for number in [1, 2, 3]: break .. versionadded:: 0.7.0 """ error_template = 'Found useless node: {0}' code = 328
[docs]@final class UselessExceptCaseViolation(ASTViolation): """ Forbids to use meaningless ``except`` cases. Reasoning: Using ``except`` cases that just reraise the same exception is error-prone. You can increase your stacktrace, silence some potential exceptions, and screw things up. It also does not make any sense to do so. Solution: Remove ``except`` case or make sure it makes sense. Example:: # Correct: try: ... except IndexError: sentry.log() raise ValueError() # Wrong: try: ... except TypeError: raise .. versionadded:: 0.7.0 """ error_template = 'Found useless `except` case' code = 329
[docs]@final class UselessOperatorsViolation(ASTViolation): """ Forbids the use of unnecessary operators in your code. You can write: ``5.4`` and ``+5.4``. There's no need to use the second version. Similarly ``--5.4``, ``---5.4``, ``not not foo``, and ``~~42`` contain unnecessary operators. Reasoning: This is done for consistency reasons. Solution: Omit unnecessary operators. Example:: # Correct: profit = 3.33 profit = -3.33 inverse = ~5 complement = not foo # Wrong: profit = +3.33 profit = --3.33 profit = ---3.33 number = ~~42 bar = not not foo .. versionadded:: 0.8.0 """ code = 330 error_template = 'Found unnecessary operator: {0}'
[docs]@final class InconsistentReturnVariableViolation(ASTViolation): """ Forbids local variable that are only used in ``return`` statements. We also allow cases when variable is assigned, then there are some other statements without direct variable access, and the variable is returned. We reserve this use-case to be able to do some extra work before the function returns. We also allow to return partial, sorted, or modified tuple items that are defined just above. Reasoning: This is done for consistency and more readable source code. Solution: Return the expression itself, instead of creating a temporary variable. Example:: # Correct: def some_function(): return 1 def other_function(): some_value = 1 do_something(some_value) return some_value # Wrong: def some_function(): some_value = 1 return some_value .. versionadded:: 0.9.0 .. versionchanged:: 0.14.0 """ error_template = 'Found variables that are only used for `return`: {0}' code = 331
[docs]@final class WalrusViolation(ASTViolation): """ Forbids local variable that are only used in ``return`` statements. This violation can only be thrown on ``python3.8+``. Reasoning: Code with ``:=`` is hardly readable. It has big problems with scoping and reading order. And it can lead to a huge mess inside your code. Python is not expression-based. Solution: Don't use fancy stuff, use good old assignments. Example:: # Correct: some = call() if some: print(some) # Wrong: if some := call(): print(some) .. versionadded:: 0.14.0 """ error_template = 'Found walrus operator' code = 332
[docs]@final class ImplicitComplexCompareViolation(ASTViolation): """ Forbids to have implicit complex compare expressions. Reasoning: Two compares in python that are joined with ``and`` operator mean that you indeed have a complex compare with tree operators. Solution: Refactor your compare without ``and`` but with the third operator. Notice, that you might have to change the ordering. Example:: # Correct: if three < two < one: ... # Wrong: if one > two and two > three: ... .. versionadded:: 0.10.0 """ code = 333 error_template = 'Found implicit complex compare'
[docs]@final class ReversedComplexCompareViolation(ASTViolation): """ Forbids to have reversed order complex compare expressions. Reasoning: Compares where comparators start from the lowest element are easier to read than one that start from the biggest one. It is also possible to write the same expression in two separate way, which is incosistent. Solution: Reverse the order, so the smallest element comes the first and the biggest one comes the last. Example:: # Correct: if three < two < one: ... # Wrong: if one > two > three: ... .. versionadded:: 0.10.0 """ code = 334 error_template = 'Found reversed complex compare'
[docs]@final class WrongLoopIterTypeViolation(ASTViolation): """ Forbids to use wrong ``for`` loop iter targets. We forbid to use: - Lists and list comprehensions - Sets and set comprehensions - Dicts and dict comprehensions - Generator expressions - Empty tuples Reasoning: Using lists, dicts, and sets do not make much sense. You can use tuples instead. Using comprehensions implicitly create a two level loops, that are hard to read and deal with. Solution: Use tuples to create explicit iterables for ``for`` loops. In case you are using a comprehension, create a new variable. Example:: # Correct: for person in ('Kim', 'Nick'): ... # Wrong: for person in ['Kim', 'Nick']: ... .. versionadded:: 0.10.0 .. versionchanged:: 0.12.0 """ code = 335 error_template = 'Found incorrect `for` loop iter type'
[docs]@final class ExplicitStringConcatViolation(ASTViolation): """ Forbids explicit string concat in favour of ``.format`` method. However, we still allow multiline string concat as a way to write long strings that does not fit the 80-chars rule. Reasoning: When formating strings one must use ``.format`` and not any other formatting methods like ``%``, ``+``, or ``f``. This is done for consistency reasons. Solution: Join strings together if you can, or use ``.format`` method. Example:: # Correct: x = 'ab: {0}'.format(some_data) # Wrong: x = 'a' + 'b: ' + some_data .. versionadded:: 0.12.0 """ code = 336 error_template = 'Found explicit string concat'
[docs]@final class MultilineConditionsViolation(ASTViolation): """ Forbids multiline conditions. Reasoning: This way of writing conditions hides the inner complexity this line has. And it decreases readability of the code. Solution: Divide multiline conditions to some ``if`` condition. Or use variables. Example:: # Correct: if isinstance(node.test, ast.UnaryOp): if isinstance(node.test.op, ast.Not): ... # Wrong: if isinstance(node.test, ast.UnaryOp) and isinstance( node.test.op, ast.Not, ): ... .. versionadded:: 0.9.0 .. versionchanged:: 0.11.0 """ error_template = 'Found multiline conditions' code = 337 previous_codes = {465}
[docs]@final class WrongMethodOrderViolation(ASTViolation): """ Forbids to have incorrect order of methods inside a class. We follow the same ordering: - ``__new__`` - ``__init__`` - ``__call__`` - ``__await__`` - public and magic methods - protected methods - private methods (we discourage using them) We follow "Newspaper order" where the most important things come first. Reasoning: It is hard to read classes where API declarations are bloated with implementation details. We need to see the important stuff first, then we can go deeper in case we are interested. Solution: Reorder methods inside your class to match our format. .. versionadded:: 0.12.0 """ error_template = 'Found incorrect order of methods in a class' code = 338
[docs]@final class NumberWithMeaninglessZeroViolation(TokenizeViolation): """ Forbids to use meaningless zeros. We discorauge using meaningless zeros in float, binary, octal, hex, and exponential numbers. Reasoning: There are ~infinite ways to write these numbers by adding meaningless leading zeros to the number itself. ``0b1`` is the same as ``0b01`` and ``0b001``. How a language can be called consistent if you can write numbers in an infinite ways? It hurts readability and understanding of your code. Solution: Remove meaningless leading zeros. Example:: # Correct: numbers = [1.5, 0b1, 0o2, 0x5, 10e10] # Wrong: numbers = [1.50, 0b00000001, 0o0002, 0x05, 10e010] .. versionadded:: 0.12.0 """ error_template = 'Found number with meaningless zeros: {0}' code = 339
[docs]@final class PositiveExponentViolation(TokenizeViolation): """ Forbids to extra ``+`` signs in the exponent. Reasoning: Positive exponent is positive by default, there's no need to write an extra ``+`` sign. We enforce consistency with this rule. Solution: Remove meaningless ``+`` sign from the exponent. Example:: # Correct: number = 1e1 + 1e-1 # Wrong: number = 1e+1 .. versionadded:: 0.12.0 """ error_template = 'Found exponent number with positive exponent: {0}' code = 340
[docs]@final class WrongHexNumberCaseViolation(TokenizeViolation): """ Forbids to use letters as hex numbers. Reasoning: One can write ``0xA`` and ``0xa`` which is inconsistent. This rule enforces upper-case letters in hex numbers. Solution: Use uppercase letters in hex numbers. Example:: # Correct: number = 0xABCDEF # Wrong: number = 0xabcdef .. versionadded:: 0.12.0 """ error_template = 'Found wrong hex number case: {0}' code = 341
[docs]@final class ImplicitRawStringViolation(TokenizeViolation): r""" Forbids to use ``\\`` escape sequences inside regular strings. Reasoning: It is hard to read escape sequencse inside regular strings, because they use ``\\`` double backslash for a single character escape. Solution: Use raw strings ``r''`` to rewrite the escape sequence with a ``\`` single backslash. Example:: # Correct: escaped = [r'\n', '\n'] # Wrong: escaped = '\\n' .. versionadded:: 0.12.0 """ error_template = 'Found implicit raw string: {0}' code = 342
[docs]@final class BadComplexNumberSuffixViolation(TokenizeViolation): """ Forbids to use uppercase complex number suffix. Reasoning: Numbers should be consistent. Solution: Use lowercase suffix for imaginary part. Example:: # Correct: complex_number = 1j # Wrong: complex_number = 1J .. versionadded:: 0.12.0 """ error_template = 'Found wrong complex number suffix: {0}' code = 343
[docs]@final class ZeroDivisionViolation(ASTViolation): """ Forbids to explicitly divide by zero. Reasoning: This will just throw ``ZeroDivisionError`` in case that's what you need: just throw it. No need to use undefined meth behaviours. Or it might be just a typo / mistake, then fix it. Solution: Use ``ZeroDivisionError`` or fix your number not to be ``0``. Example:: # Correct: raise ZeroDivisionError() # Wrong: 1 / 0 .. versionadded:: 0.12.0 """ error_template = 'Found explicit zero division' code = 344
[docs]@final class MeaninglessNumberOperationViolation(ASTViolation): """ Forbids to use meaningless math operations with ``0`` and ``1``. Reasoning: Adding and substracting zero does not change the value. There's no need to do that. Multipling by zero is also redundant: it can be replaced with explicit ``0`` assign. Multiplying and dividing by ``1`` is also meaningless. Solution: Remove useless zero operations. Example:: # Correct: number = 1 zero = 0 one = 1 # Wrong: number = 1 + 0 * 1 zero = some * 0 / 1 one = some ** 0 ** 1 .. versionadded:: 0.12.0 """ error_template = 'Found meaningless number operation' code = 345
[docs]@final class OperationSignNegationViolation(ASTViolation): """ Forbids to have double minus operations. Reasoning: Having two operations is harder than having just one. Two negations are harder than one positive expression. Two negations equal to one positive expression. Positive and negative equal to one negative. Solution: Replace double minus operation to a single one with plus. Replace 'plus-minus' operation to a single one with minus. Example:: # Correct: number = 3 + 1 number += 6 number -= 2 # Wrong: number = 3 - -1 number -= -6 number += -2 .. versionadded:: 0.12.0 """ error_template = 'Found wrong operation sign' code = 346
[docs]@final class VagueImportViolation(ASTViolation): """ Forbids imports that may cause confusion outside of the module. Names that we forbid to import: - Common names like ``dumps`` and ``loads`` - Names starting with ``to_`` and ``from_`` - Too short names like ``Q`` or ``F``, but we are fine with ``_`` Reasoning: See ``datetime.*`` in code? You know that it's from datetime. See ``BaseView`` in a Django project? You know where it is from. See ``loads``? It can be anything: ``yaml``, ``toml``, ``json``, etc. We are also enforcing consitency with our naming too-short rules here. Solution: Use package level imports or import aliases. See :py:data:`~wemake_python_styleguide.constants.VAGUE_IMPORTS_BLACKLIST` for the full list of bad import names. Example:: # Correct: import json import dumps # package names are not checked from json import loads as json_loads # Wrong: from json import loads .. versionadded:: 0.13.0 .. versionchanged:: 0.14.0 """ error_template = 'Found vague import that may cause confusion: {0}' code = 347
[docs]@final class LineStartsWithDotViolation(TokenizeViolation): """ Forbids to start lines with a dot. Reasoning: We enforce strict consitency rules about how to break lines. We also enforce strict rules about multi-line parameters. Starting new lines with the dot means that this rule is broken. Solution: Use ``()`` to break lines in a complex expression. Example:: # Correct: some = MyModel.objects.filter( ..., ).exclude( ..., ).annotate( ..., ) # Wrong some = ( MyModel.objects.filter(...) .exclude(...) .annotate(...) ) .. versionadded:: 0.13.0 """ error_template = 'Found a line that starts with a dot' code = 348
[docs]@final class RedundantSubscriptViolation(ASTViolation): """ Forbids the use of redundant components in a subscript's slice. Reasoning: We do it for consistency reasons. Example:: # Correct: array[:7] array[3:] # Wrong: x[0:7] x[3:None] .. versionadded:: 0.13.0 """ error_template = 'Found redundant subscript slice' code = 349
[docs]@final class AugmentedAssignPatternViolation(ASTViolation): """ Enforce using augmented assign pattern. Reasoning: ``a += b`` is short and correct version of ``a = a + b``. Why not using the short version? Example:: # Correct: a += b # Wrong: a = a + b .. versionadded:: 0.13.0 """ error_template = 'Found usable augmented assign pattern' code = 350
[docs]@final class UnnecessaryLiteralsViolation(ASTViolation): """ Forbids the use of unnecessary literals in your code. Reasoning: We discourage using primitive calls to get default type values. There are better ways to get these values. Solution: Use direct default values of the given type Example:: # Correct: default = 0 # Wrong: default = int() .. versionadded:: 0.13.0 """ error_template = 'Found unnecessary literals' code = 351
[docs]@final class MultilineLoopViolation(ASTViolation): """ Forbids multiline loops. Reasoning: It decreased the readability of the code. Solution: Use single line loops and create new variables in case you need to fit too many logic inside the loop definition. Example:: # Correct: for num in some_function(arg1, arg2): ... # Wrong: for num in range( arg1, arg2, ): ... .. versionadded:: 0.13.0 """ error_template = 'Found multiline loop' code = 352
[docs]@final class IncorrectYieldFromTargetViolation(ASTViolation): """ Forbids to use ``yield from`` with several nodes. We allow to ``yield from`` tuples, names, attributes, calls, and subscripts. Reasoning: We enforce consitency when yielding values from tuple instead of any other types. It also might be an error when you try to ``yield from`` something that is not iterable. Solution: Use allowed node types with ``yield from``. Example:: # Correct: yield from (1, 2, 3) yield from some # Wrong: yield from [1, 2, 3] .. versionadded:: 0.13.0 """ error_template = 'Found incorrect `yield from` target' code = 353
[docs]@final class ConsecutiveYieldsViolation(ASTViolation): """ Forbids to have consecutive ``yield`` expressions. We raise this violation when we find at least two consecutive ``yield`` expressions. Reasoning: One can write multiple ``yield`` nodes in a row. That's incosistent. Because we have ``yield from`` form. Solution: It can be easily changed to ``yield from (...)`` format. .. versionadded:: 0.13.0 """ error_template = 'Found consecutive `yield` expressions' code = 354
[docs]@final class BracketBlankLineViolation(TokenizeViolation): """ Forbids useless blank lines before and after brackets. Reasoning: We do this for consistency. Solution: Remove blank lines from the start and from the end of a collection. Example:: # Correct: arr = [ 1, 2, ] # Wrong: arr = [ 1, 2, ] .. versionadded:: 0.13.0 """ error_template = 'Found an unnecessary blank line before a bracket' code = 355
[docs]@final class IterableUnpackingViolation(ASTViolation): """ Forbids unnecessary iterable unpacking. Reasoning: We do this for consistency. Solution: Do not use iterables unpacking, when it's not necessary. Example:: # Correct: [1, *numbers, 99] {*iterable, *other_iterable} list(iterable) first, *iterable = other_iterable # Wrong: [*iterable] *iterable, = other_iterable .. versionadded:: 0.13.0 """ error_template = 'Found an unnecessary iterable unpacking' code = 356
[docs]@final class LineCompriseCarriageReturnViolation(TokenizeViolation): r""" Forbids to use ``\r`` (carriage return) in line breaks. Reasoning: We enforce Unix-style newlines. We only use newlines (``\n``), not carriage returns. So ``\r`` line breaks not allowed in code. Solution: Use only ``\n`` (not ``\r\n`` or ``\r``) to break lines. .. versionadded:: 0.14.0 """ error_template = r'Found a ``\r`` (carriage return) line break' code = 357
[docs]@final class FloatZeroViolation(TokenizeViolation): """ Forbids to use float zeros: ``0.0``. Reasoning: Float zeros can be used as variable values which may lead to typing bugs when trying to perform an operation between an int number and the float zero. Solution: Use int zeros (0). If a float is needed, it should be cast explicitly. Example:: # Correct: zero = 0 # Wrong: zero = 0.0 .. versionadded:: 0.15.0 """ code = 358 error_template = 'Found a float zero (0.0)'