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.
Summary¶
LocalFolderImportViolation |
Forbids to have imports relative to the current folder. |
DottedRawImportViolation |
Forbids to use imports like import os.path . |
UnicodeStringViolation |
Forbids to use u string prefix. |
UnderscoredNumberViolation |
Forbids to use underscores (_ ) in numbers. |
PartialFloatViolation |
Forbids to use partial floats like .05 or 23. . |
FormattedStringViolation |
Forbids to use f strings. |
RequiredBaseClassViolation |
Forbids to write classes without base classes. |
MultipleIfsInComprehensionViolation |
Forbids to have multiple if statements inside list comprehensions. |
ConstantComparisonViolation |
Forbids to have comparisons between two literals. |
ComparisonOrderViolation |
Forbids comparision where argument doesn’t come first. |
BadNumberSuffixViolation |
Forbids to use capital X , O , B , and E in numbers. |
MultipleInComparisonViolation |
Forbids comparision where multiple in checks. |
RedundantComparisonViolation |
Forbids to have comparisons between the same variable. |
MissingSpaceBetweenKeywordAndParenViolation |
Enforces to separate parenthesis from the keywords with spaces. |
WrongConditionalViolation |
Forbids using if statements that use invalid conditionals. |
ObjectInBaseClassesListViolation |
Forbids extra object in parent classes list. |
MultipleContextManagerAssignmentsViolation |
Forbids multiple assignment targets for context managers. |
ParametersIndentationViolation |
Forbids to use incorrect parameters indentation. |
ExtraIndentationViolation |
Forbids to use extra indentation. |
WrongBracketPositionViolation |
Forbids to use extra indentation. |
MultilineFunctionAnnotationViolation |
Forbids to use multi-line function type annotations. |
UppercaseStringModifierViolation |
Forbids to use uppercase string modifiers. |
IncorrectMultilineStringViolation |
Forbids to use triple quotes for singleline strings. |
EmptyLineAfterCodingViolation |
Enforces to have an extra empty line after the coding comment. |
InconsistentReturnViolation |
Enforces to have consistent return statements. |
InconsistentYieldViolation |
Enforces to have consistent yield statements. |
ImplicitStringConcatenationViolation |
Forbids to use implicit string contacatenation. |
UselessContinueViolation |
Forbids to use meaningless continue node in loops. |
UselessNodeViolation |
Forbids to use meaningless nodes. |
UselessExceptCaseViolation |
Forbids to use meaningless except cases. |
Consistency checks¶
-
class
LocalFolderImportViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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
New in version 0.1.0.
-
error_template
= 'Found local folder import'¶
-
code
= 300¶
-
class
DottedRawImportViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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
New in version 0.1.0.
-
error_template
= 'Found dotted raw import: {0}'¶
-
code
= 301¶
-
class
UnicodeStringViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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'
New in version 0.1.0.
-
code
= 302¶
-
error_template
= 'Found unicode string prefix: {0}'¶
-
class
UnderscoredNumberViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Forbids to use underscores (
_
) in numbers.- Reasoning:
- It is possible to write
1000
in three different ways:1_000
,10_00
, and100_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
New in version 0.1.0.
-
code
= 303¶
-
error_template
= 'Found underscored number: {0}'¶
-
class
PartialFloatViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Forbids to use partial floats like
.05
or23.
.- 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.
New in version 0.1.0.
-
code
= 304¶
-
error_template
= 'Found partial float: {0}'¶
-
class
FormattedStringViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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.
Example:
# Wrong: f'Result is: {2 + 2}' # Correct: 'Result is: {0}'.format(2 + 2) 'Hey {user}! How are you?'.format(user='sobolevn')
New in version 0.1.0.
-
error_template
= 'Found `f` string'¶
-
code
= 305¶
-
class
RequiredBaseClassViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Forbids to write classes without base classes.
- 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.
- Solution:
- Add a base class.
Example:
# Correct: class Some(object): ... # Wrong: class Some: ...
New in version 0.1.0.
-
error_template
= 'Found class without a base class: {0}'¶
-
code
= 306¶
-
class
MultipleIfsInComprehensionViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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. Usefilter()
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')]
New in version 0.1.0.
-
error_template
= 'Found list comprehension with multiple `if`s'¶
-
code
= 307¶
-
class
ConstantComparisonViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Forbids to have comparisons between two literals.
- Reasoning:
- When two constants are compared it is typically an indication of a mistake, since the Boolean value of the comparison, will always be the same.
- Solution:
- Remove the constant comparison and any associated dead code.
Example:
# Wrong: if 60 * 60 < 1000: do_something() else: do_something_else() # Correct: do_something_else()
New in version 0.3.0.
-
error_template
= 'Found constant comparison'¶
-
code
= 308¶
-
class
ComparisonOrderViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Forbids comparision 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 comparison!
- Solution:
- Refactor your comparison expression, place the argument first.
Example:
# Correct: if some_x > 3: if 3 < some_x < 10: # Wrong: if 3 < some_x:
New in version 0.3.0.
-
error_template
= 'Found reversed comparison order'¶
-
code
= 309¶
-
class
BadNumberSuffixViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Forbids to use capital
X
,O
,B
, andE
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 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
New in version 0.3.0.
-
error_template
= 'Found bad number suffix: {0}'¶
-
code
= 310¶
-
class
MultipleInComparisonViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Forbids comparision where multiple
in
checks.- Reasoning:
- Using multiple
in
is unreadable. - Solution:
- Refactor your comparison expression to use several
and
conditions or separateif
statements in case it is appropriate.
Example:
# Correct: if item in bucket and bucket in master_list_of_buckets: if x_coord in line and line in square: # Wrong: if item in bucket in master_list_of_buckets: if x_cord in line in square:
New in version 0.3.0.
-
error_template
= 'Found multiple `in` comparisons'¶
-
code
= 311¶
-
class
RedundantComparisonViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Forbids to have comparisons 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 comparison will always be the same.
- Solution:
- Remove the same variable comparison and any associated dead code.
Example:
# Wrong: a = 1 if a < a: do_something() else: do_something_else() # Correct: do_something()
New in version 0.3.0.
-
error_template
= 'Found comparison between same variable'¶
-
code
= 312¶
-
class
MissingSpaceBetweenKeywordAndParenViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Enforces to separate parenthesis from the keywords with spaces.
- Reasoning:
- Some people use
return
andyield
keywords as functions. The same happened to good oldprint
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)
New in version 0.3.0.
-
error_template
= 'Found parens right after a keyword'¶
-
code
= 313¶
-
class
WrongConditionalViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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: ...
New in version 0.3.0.
-
error_template
= 'Conditional always evaluates to same result'¶
-
code
= 314¶
-
class
ObjectInBaseClassesListViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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): ...
New in version 0.3.0.
-
error_template
= 'Founded extra `object` in parent classes list'¶
-
code
= 315¶
-
class
MultipleContextManagerAssignmentsViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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: ...
New in version 0.6.0.
-
error_template
= 'Found context manager with too many assignments'¶
-
code
= 316¶
-
class
ParametersIndentationViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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='')
Everything else is considered a violation. This rule checks: lists, sets, tuples, dicts, calls, functions, methods, and classes.
New in version 0.6.0.
-
error_template
= 'Found incorrect multi-line parameters'¶
-
code
= 317¶
-
class
ExtraIndentationViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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')
New in version 0.6.0.
-
error_template
= 'Found extra indentation'¶
-
code
= 318¶
-
class
WrongBracketPositionViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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:
- Place bracket on the same line, when a single line expression. Or place the bracket on a new line when 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.
New in version 0.6.0.
-
error_template
= 'Found bracket in wrong position'¶
-
code
= 319¶
-
class
MultilineFunctionAnnotationViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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.
New in version 0.6.0.
-
error_template
= 'Found multi-line function type annotation'¶
-
code
= 320¶
-
class
UppercaseStringModifierViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Forbids to use uppercase string modifiers.
- Reasoning:
- String modifiers should be consistent.
- Solution:
- Use lowercase modifiers should be written in lowercase.
Example:
# Correct: some_string = r'/regex/' some_bytes = b'123' # Wrong: some_string = R'/regex/' some_bytes = B'123'
New in version 0.6.0.
-
error_template
= 'Found uppercase string modifier: {0}'¶
-
code
= 321¶
-
class
IncorrectMultilineStringViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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.
New in version 0.7.0.
-
error_template
= 'Found incorrect multi-line string'¶
-
code
= 322¶
-
class
EmptyLineAfterCodingViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Enforces to have an extra empty line after the
coding
comment.- Reasoning:
- This is done for pure consistency.
- Solution:
- Add an empty line between
coding
magic comment and your code.
Example:
# Correct: # coding: utf-8 SOME_VAR = 1 # Wrong: # coding: utf-8 SOME_VAR = 1
New in version 0.7.0.
-
error_template
= 'Found missing empty line between `coding` magic comment and code'¶
-
code
= 323¶
-
class
InconsistentReturnViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Enforces to have consistent
return
statements.Rules are: 1. if any
return
has a value, allreturn
nodes should have a value 2. do not placereturn
without value at the end of a functionThis rule respects
mypy
style of placingreturn
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. Removereturn
statement from the function end.
Example:
# Correct: def function(): if some: return 2 return 1 # Wrong: def function(): if some: return return 1 def function(): if some: print(some) return
New in version 0.7.0.
-
error_template
= 'Found inconsistent `return` statement'¶
-
code
= 324¶
-
class
InconsistentYieldViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.ASTViolation
Enforces to have consistent
yield
statements.Rules are: 1. if any
yield
has a value, allyield
nodes should have a valueThis rule respects
mypy
style of placingyield
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
New in version 0.7.0.
-
error_template
= 'Found inconsistent `yield` statement'¶
-
code
= 325¶
-
class
ImplicitStringConcatenationViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.TokenizeViolation
Forbids to use implicit string contacatenation.
- Reasoning:
- This is error-prone, since you can possible 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'
New in version 0.7.0.
-
error_template
= 'Found implicit string concatenation'¶
-
code
= 326¶
-
class
UselessContinueViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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) # Wrong: for number in [1, 2, 3]: print(number) continue
New in version 0.7.0.
-
error_template
= 'Found useless `continue` at the end of the loop'¶
-
code
= 327¶
-
class
UselessNodeViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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 any sense.
Example:
# Wrong: for number in [1, 2, 3]: break
New in version 0.7.0.
-
error_template
= 'Found useless node: {0}'¶
-
code
= 328¶
-
class
UselessExceptCaseViolation
(node, text=None)[source]¶ Bases:
wemake_python_styleguide.violations.base.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 any sense.
Example:
# Correct: try: ... except IndexError: sentry.log() raise ValueError() # Wrong: try: ... except TypeError: raise
New in version 0.7.0.
-
error_template
= 'Found useless `except` case'¶
-
code
= 329¶