Source code for wemake_python_styleguide.violations.complexity

"""
These checks find flaws in your application design.

We try to stick to "the magical 7 ± 2 number" when counting things.
https://en.wikipedia.org/wiki/The_Magical_Number_Seven,_Plus_or_Minus_Two

That's how many objects we can keep in our memory at a time.
We try hard not to exceed the memory capacity limit.

You can also find interesting reading about "Cognitive complexity":
https://www.sonarsource.com/docs/CognitiveComplexity.pdf

Note:
    Simple is better than complex.
    Complex is better than complicated.

See also:
    https://sobolevn.me/2019/10/complexity-waterfall

.. currentmodule:: wemake_python_styleguide.violations.complexity

Summary
-------

.. autosummary::
   :nosignatures:

   JonesScoreViolation
   TooManyImportsViolation
   TooManyModuleMembersViolation
   TooManyImportedNamesViolation
   OverusedExpressionViolation
   TooManyLocalsViolation
   TooManyArgumentsViolation
   TooManyReturnsViolation
   TooManyExpressionsViolation
   TooManyMethodsViolation
   TooManyBaseClassesViolation
   TooManyDecoratorsViolation
   TooManyAwaitsViolation
   TooManyAssertsViolation
   TooDeepAccessViolation
   TooDeepNestingViolation
   LineComplexityViolation
   TooManyConditionsViolation
   TooManyElifsViolation
   TooManyForsInComprehensionViolation
   TooManyExceptCasesViolation
   OverusedStringViolation
   TooLongYieldTupleViolation
   TooLongCompareViolation
   TooLongTryBodyViolation
   TooManyPublicAttributesViolation
   CognitiveComplexityViolation
   CognitiveModuleComplexityViolation
   TooLongCallChainViolation
   TooComplexAnnotationViolation
   TooManyImportedModuleMembersViolation
   TooLongTupleUnpackViolation
   TooComplexFormattedStringViolation
   TooManyRaisesViolation

Module complexity
-----------------

.. autoclass:: JonesScoreViolation
.. autoclass:: TooManyImportsViolation
.. autoclass:: TooManyModuleMembersViolation
.. autoclass:: TooManyImportedNamesViolation
.. autoclass:: OverusedExpressionViolation

Structure complexity
--------------------

.. autoclass:: TooManyLocalsViolation
.. autoclass:: TooManyArgumentsViolation
.. autoclass:: TooManyReturnsViolation
.. autoclass:: TooManyExpressionsViolation
.. autoclass:: TooManyMethodsViolation
.. autoclass:: TooManyBaseClassesViolation
.. autoclass:: TooManyDecoratorsViolation
.. autoclass:: TooManyAwaitsViolation
.. autoclass:: TooManyAssertsViolation
.. autoclass:: TooDeepAccessViolation
.. autoclass:: TooDeepNestingViolation
.. autoclass:: LineComplexityViolation
.. autoclass:: TooManyConditionsViolation
.. autoclass:: TooManyElifsViolation
.. autoclass:: TooManyForsInComprehensionViolation
.. autoclass:: TooManyExceptCasesViolation
.. autoclass:: OverusedStringViolation
.. autoclass:: TooLongYieldTupleViolation
.. autoclass:: TooLongCompareViolation
.. autoclass:: TooLongTryBodyViolation
.. autoclass:: TooManyPublicAttributesViolation
.. autoclass:: CognitiveComplexityViolation
.. autoclass:: CognitiveModuleComplexityViolation
.. autoclass:: TooLongCallChainViolation
.. autoclass:: TooComplexAnnotationViolation
.. autoclass:: TooManyImportedModuleMembersViolation
.. autoclass:: TooLongTupleUnpackViolation
.. autoclass:: TooComplexFormattedStringViolation
.. autoclass:: TooManyRaisesViolation

"""

from typing_extensions import final

from wemake_python_styleguide.violations.base import (
    ASTViolation,
    MaybeASTViolation,
    SimpleViolation,
)


[docs]@final class JonesScoreViolation(SimpleViolation): """ Forbid modules with complex lines. We are using the Jones Complexity algorithm to count module's score. See :py:class:`~.LineComplexityViolation` for details of per-line-complexity. How it is done: we count complexity per line, then measure the median complexity across the lines in the whole module. Reasoning: Having complex modules will decrease your code maintainability. Solution: Refactor the module contents. Configuration: This rule is configurable with ``--max-jones-score``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_JONES_SCORE` .. versionadded:: 0.1.0 See also: https://github.com/Miserlou/JonesComplexity """ error_template = 'Found module with high Jones Complexity score: {0}' code = 200
[docs]@final class TooManyImportsViolation(SimpleViolation): """ Forbid modules with too many imports. Namespaces are one honking great idea -- let's do more of those! Reasoning: Having too many imports without prefixes is quite expensive. You have to memorize all the source locations of the imports and sometimes it is hard to remember what kind of functions and classes are already injected into your context. It is also a questionable design if a single module has a lot of imports. Why would a single module have so many dependencies? So, the module becomes too coupled. Solution: Refactor the imports to import a common namespace. Something like ``from package import module`` and then use it like ``module.function()``. Or refactor your code and split the complex module into several modules. We do not make any distinction between ``import`` and ``from ... import ...``. Configuration: This rule is configurable with ``--max-imports``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_IMPORTS` .. versionadded:: 0.1.0 """ error_template = 'Found module with too many imports: {0}' code = 201
[docs]@final class TooManyModuleMembersViolation(SimpleViolation): """ Forbid too many classes and functions in a single module. Reasoning: Having many classes and functions in a single module is a bad thing. Soon it will be hard to read through this code and understand it. Solution: It is better to split this module into several modules or a package. We do not make any distinctions between classes and functions in this check. They are treated as the same unit of logic. We also do not care about functions and classes being public or not. However, methods are counted separately on a per-class basis. Configuration: This rule is configurable with ``--max-module-members``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_MODULE_MEMBERS` .. versionadded:: 0.1.0 """ error_template = 'Found too many module members: {0}' code = 202
[docs]@final class TooManyImportedNamesViolation(SimpleViolation): """ Forbid modules with too many imported names. Namespaces are one honking great idea -- let's do more of those! Reasoning: Having too many imported names without prefixes is quite expensive. You have to memorize all the source locations of the imports and sometimes it is hard to remember what kind of functions and classes are already injected into your context. It is also a questionable design if a single module has a lot of imports. Why would a single module have so many dependencies? So, the module becomes too coupled. Solution: Refactor the imports to import a common namespace. Something like ``from package import module`` and then use it like ``module.function()``. Or refactor your code and split the complex module into several modules. Example:: # Correct: import module # 1 imported name # Wrong: from module import func1, func2, ..., funcN # N imported names We do not make any differences between ``import`` and ``from ... import ...``. Configuration: This rule is configurable with ``--max-imported-names``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_IMPORTED_NAMES` .. versionadded:: 0.12.0 """ error_template = 'Found module with too many imported names: {0}' code = 203
[docs]@final class OverusedExpressionViolation(ASTViolation): """ Forbid overused expressions in a module, function or method. What do we call an "overused expression"? When you use any expression (like ``user_dict['age']`` for example) inside your code, you always have to track that you are not using it "too much" because if that expression is everywhere inside your code, it is a sign of a problem. It means that you are missing an abstraction. We check for overused expressions on two levels: - per each function - per all module Related to :class:`~TooManyExpressionsViolation`. Reasoning: Overusing expressions leads to losing the parts that can and should be refactored into variables, methods, and properties of objects. Solution: Refactor expressions to be an attribute, a method, or a new variable. Configuration: This rule is configurable with ``--max-module-expressions``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_MODULE_EXPRESSIONS` And with ``--max-function-expressions``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_FUNCTION_EXPRESSIONS` .. versionadded:: 0.12.0 .. versionchanged:: 0.14.0 """ error_template = 'Found overused expression: {0}' code = 204
# Functions and classes:
[docs]@final class TooManyLocalsViolation(ASTViolation): """ Forbid too many local variables in the unit of code. Reasoning: Having too many variables in a single function is a bad thing. Soon, you will have trouble understanding what this variable means. It will also become hard to name new variables. Solution: If you have too many variables in a function, you have to refactor it. What counts as a local variable? We only count a variable as local in the following case: it is assigned inside the function body. We do not count variables defined inside comprehensions as local variables, since it is impossible to use them outside of the comprehension. Example:: def first_function(param): first_var = 1 def second_function(argument): second_var = 1 argument = int(argument) third_var, _ = some_call() In this example we will count as locals only several variables: 1. ``first_var``, because it is assigned inside the function's body 2. ``second_var``, because it is assigned inside the function's body 3. ``argument``, because it is reassigned inside the function's body 4. ``third_var``, because it is assigned inside the function's body Please, note that ``_`` is a special case. It is not counted as a local variable. Since by design it means: do not count me as a real variable. Configuration: This rule is configurable with ``--max-local-variables``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_LOCAL_VARIABLES` .. versionadded:: 0.1.0 """ error_template = 'Found too many local variables: {0}' code = 210
[docs]@final class TooManyArgumentsViolation(ASTViolation): """ Forbid too many arguments for a function or method. Reasoning: This is an indicator of a bad design. When a function requires many arguments it is a sign that it should be refactored. It also indicates that the function does too many things at once. Solution: Split the function into several functions. Then it will be easier to use them. Configuration: This rule is configurable with ``--max-arguments``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_ARGUMENTS` .. versionadded:: 0.1.0 """ error_template = 'Found too many arguments: {0}' code = 211
[docs]@final class TooManyReturnsViolation(ASTViolation): """ Forbid placing too many ``return`` statements in a function. Reasoning: When there are too many ``return`` keywords, functions are hard to test. They are also hard to read and hard to change and keep everything inside your head at once. Solution: Change your design. Split the function into multiple functions. Configuration: This rule is configurable with ``--max-returns``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_RETURNS` .. versionadded:: 0.1.0 """ error_template = 'Found too many return statements: {0}' code = 212
[docs]@final class TooManyExpressionsViolation(ASTViolation): """ Forbid putting too many expressions in a single function. This rule is quite similar to "max lines" in a function, but is much nicer because we don't count lines, we count real code entities. This way adding just several extra empty lines for readability will never trigger this violation. Related to :class:`~OverusedExpressionViolation`. Reasoning: When there are too many expressions it means that this function does too many things at once. It has too much logic. Solution: Split function into several functions, refactor your API. Configuration: This rule is configurable with ``--max-expressions``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_EXPRESSIONS` .. versionadded:: 0.1.0 See also: https://en.wikipedia.org/wiki/Expression_(computer_science) """ error_template = 'Found too many expressions: {0}' code = 213
[docs]@final class TooManyMethodsViolation(ASTViolation): """ Forbid too many methods in a single class. Reasoning: Having too many methods might lead to the "God object" anti-pattern. This kind of object can handle everything. So, in the end, your code becomes too hard to maintain and test. Solution: What to do if you have too many methods in a single class? Split this class into several classes, then use composition or inheritance to refactor your code. This will protect you from the "God object" anti-pattern. We do not make any distinctions between instance and class methods. We also do not care about functions and classes being public or not. We also do not count inherited methods from parents. This rule does not count the attributes of a class. Configuration: This rule is configurable with ``--max-methods``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_METHODS` .. versionadded:: 0.1.0 See also: https://en.wikipedia.org/wiki/God_object """ error_template = 'Found too many methods: {0}' code = 214
[docs]@final class TooManyBaseClassesViolation(ASTViolation): """ Restrict the maximum number of base classes. Reasoning: It is almost never possible to navigate to the desired method of a parent class when you need it with multiple mixins. It is hard to understand ``mro`` and ``super`` calls. Do not overuse this technique. Solution: Reduce the number of base classes. Use composition over inheritance. Example:: # Correct: class SomeClassName(First, Second, Mixin): ... # Wrong: class SomeClassName( FirstParentClass, SecondParentClass, ThirdParentClass, CustomClass, AddedClass, ): ... Configuration: This rule is configurable with ``--max-base-classes``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_BASE_CLASSES` .. versionadded:: 0.3.0 .. versionchanged:: 0.5.0 See also: https://en.wikipedia.org/wiki/Composition_over_inheritance """ error_template = 'Too many base classes: {0}' code = 215
[docs]@final class TooManyDecoratorsViolation(ASTViolation): """ Restrict the maximum number of decorators. Reasoning: When you are using too many decorators it means that you are trying to overuse the magic. You have to ask yourself: do I really know what happens inside this decorator tree? Typically, the answer will be "no". Solution: Using too many decorators typically means that you are trying to configure the behavior from outside of the class. Do not do that too much. Split functions or classes into smaller ones. Use higher order decorators. Configuration: This rule is configurable with ``--max-decorators``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_DECORATORS` This rule checks: functions, methods, and classes. .. versionadded:: 0.5.0 """ error_template = 'Too many decorators: {0}' code = 216
[docs]@final class TooManyAwaitsViolation(ASTViolation): """ Forbid placing too many ``await`` expressions in a function. Reasoning: When there are too many ``await`` keywords, functions are starting to get really complex. It is hard to tell where we are and what is going on. Solution: Change your design. Split functions into smaller ones. Configuration: This rule is configurable with ``--max-awaits``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_AWAITS` .. versionadded:: 0.10.0 """ error_template = 'Found too many await expressions: {0}' code = 217
[docs]@final class TooManyAssertsViolation(ASTViolation): """ Forbid placing too many ``assert`` statements into a function. Reasoning: When there are too many ``assert`` keywords, functions are starting to get really complex. It might indicate that your tests or contracts are too big. Solution: Create rich ``assert`` statements, use higher-level contracts, or create special guard functions. Configuration: This rule is configurable with ``--max-asserts``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_ASSERTS` .. versionadded:: 0.12.0 """ error_template = 'Found too many `assert` statements: {0}' code = 218
[docs]@final class TooDeepAccessViolation(ASTViolation): """ Forbid consecutive expressions with too deep access level. We consider only these expressions as accesses: - ``ast.Subscript`` - ``ast.Attribute`` We do not treat ``ast.Call`` as an access, since there are a lot of call-based APIs like Django ORM, builder patterns, etc. Reasoning: Having too deep access level indicates a bad design and overcomplicated data without proper API. Solution: Split the expression into variables, functions or classes. Refactor the API for your data layout. Example:: # Correct: access level = 4 self.attr.inner.wrapper[1] # Correct: access level = 1 manager.filter().exclude().annotate().values().first() # Wrong: access level = 5 self.attr.inner.wrapper.method.call() # Wrong: access level = 5 # `obj` has access level of 2: # `.attr`, `.call` # `call()` has access level of 5: # `.other`, `[0]`, `.field`, `.type`, `.boom` obj.attr.call().other[0].field.type.boom Configuration: This rule is configurable with ``--max-access-level``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_ACCESS_LEVEL` .. versionadded:: 0.12.0 """ error_template = 'Found too deep access level: {0}' code = 219
[docs]@final class TooDeepNestingViolation(ASTViolation): """ Forbid nesting blocks too deep. Reasoning: If nesting is too deep that indicates usage of complex logic and language constructions. This means that our design is not suited to handle such construction. Solution: We need to refactor our complex construction into simpler ones. We can use new functions or different constructions. .. versionadded:: 0.1.0 .. versionchanged:: 0.5.0 """ error_template = 'Found too deep nesting: {0}' code = 220
[docs]@final class LineComplexityViolation(ASTViolation): """ Forbid complex lines. We are using the Jones Complexity algorithm to count complexity. What is the Jones Complexity? It is a simple yet powerful method to count the number of ``ast`` nodes per line. If the complexity of a single line is higher than a threshold, then an error is raised. What nodes do we count? All except the following: 1. modules 2. function and classes, since they are checked differently 3. type annotations, since they do not increase the complexity Reasoning: Having a complex line indicates that you somehow managed to put too much logic inside a single line. At some point in time, you will no longer be able to understand what this line means and what it does. Solution: Split a single line into several lines: by creating new variables, statements or functions. Note, this might trigger new complexity issues. With this technique, a single new node in a line might trigger a complex refactoring process including several modules. Configuration: This rule is configurable with ``--max-line-complexity``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_LINE_COMPLEXITY` .. versionadded:: 0.1.0 See also: https://github.com/Miserlou/JonesComplexity """ error_template = 'Found line with high Jones Complexity: {0}' code = 221
[docs]@final class TooManyConditionsViolation(ASTViolation): """ Forbid conditions with too many logical operators. We use :str:`wemake_python_styleguide.constants.MAX_CONDITIONS` as a default value. Reasoning: When reading through the complex conditions you will fail to understand all the possible branches. And you will end up putting debug breakpoint on this line just to figure out how it works. Solution: We can reduce the complexity of a single ``if`` by doing two things: creating new variables or creating nested ``if`` statements. Both of these actions will trigger other complexity checks. We count ``and`` and ``or`` keywords as conditions. .. versionadded:: 0.1.0 .. versionchanged:: 0.5.0 """ error_template = 'Found a condition with too much logic: {0}' code = 222
[docs]@final class TooManyElifsViolation(ASTViolation): """ Forbid too many ``elif`` branches. We use :str:`wemake_python_styleguide.constants.MAX_ELIFS` as a default value. Reasoning: This rule is specifically important because many ``elif`` branches indicates a complex flow in your design: you are reimplementing ``switch`` in python. Solution: There are different design patterns to use instead. For example, you can use an interface that just calls a specific method without ``if``. Another option is to separate your ``if`` into multiple functions. .. versionadded:: 0.1.0 .. versionchanged:: 0.5.0 """ error_template = 'Found too many `elif` branches: {0}' code = 223
[docs]@final class TooManyForsInComprehensionViolation(ASTViolation): """ Forbid too many ``for`` statements within a comprehension. Reasoning: When reading through the complex comprehension you will fail to understand it. Solution: We can reduce the complexity of the comprehension by reducing the amount of ``for`` statements. Refactor your code to use several ``for`` loops, comprehensions, or different functions. Example:: # Wrong: ast_nodes = [ target for assignment in top_level_assigns for target in assignment.targets for _ in range(10) ] .. versionadded:: 0.3.0 """ error_template = 'Found a comprehension with too many `for` statements' code = 224
[docs]@final class TooManyExceptCasesViolation(ASTViolation): """ Forbid too many ``except`` cases in a single ``try`` clause. We use :str:`wemake_python_styleguide.constants.MAX_EXCEPT_CASES` as a default value. Reasoning: Handling too many exceptions in a single place is a good indicator of a bad design since one controlling structure will become too complex. Also, you will need to test a lot of logic paths in your application. Solution: We can reduce the complexity of this case by splitting it into multiple ``try`` cases, functions or using a decorator to handle different exceptions. .. versionadded:: 0.7.0 """ error_template = 'Found too many `except` cases: {0}' code = 225
[docs]@final class OverusedStringViolation(MaybeASTViolation): """ Forbid the overuse of string constants. We allow to use strings without any restrictions as annotations for variables, arguments, return values, and class attributes. Reasoning: When some string is used more than several time in your code, it probably means that this string is a meaningful constant and should be treated like one. Solution: Deduplicate you string usages by defining new functions or constants. Configuration: This rule is configurable with ``--max-string-usages``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_STRING_USAGES` .. versionadded:: 0.10.0 """ error_template = 'Found string constant over-use: {0}' code = 226
[docs]@final class TooLongYieldTupleViolation(ASTViolation): """ Forbid yielding tuples that are too long. Reasoning: Long yield tuples complicate generator usage. This rule helps to reduce complication. Solution: Use lists of similar type or wrapper objects. .. versionadded:: 0.10.0 """ error_template = 'Found too long yield tuple: {0}' code = 227
[docs]@final class TooLongCompareViolation(ASTViolation): """ Forbid compare expressions that are too long. Reasoning: Compare expressions that are too long indicate that there's something wrong going on in the code. Compares should not be longer than 3 or 4 items. Solution: Use several conditions, separate variables, or functions. .. versionadded:: 0.10.0 """ error_template = 'Found too long compare' code = 228
[docs]@final class TooLongTryBodyViolation(ASTViolation): """ Forbid ``try`` blocks with bodies that are too long. Reasoning: Having too many statements inside your ``try`` block can lead to situations when a statement raises an exception and you are not aware of it since it is not expected. Solution: Move things out of the ``try`` block or create new functions. The fewer lines you have in your ``try`` block - the safer you are from accidental errors. Configuration: This rule is configurable with ``--max-try-body-length``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_TRY_BODY_LENGTH` See also: https://adamj.eu/tech/2019/10/02/limit-your-try-clauses-in-python/ .. versionadded:: 0.12.0 """ error_template = 'Found too long ``try`` body length: {0}' code = 229
[docs]@final class TooManyPublicAttributesViolation(ASTViolation): """ Forbid instances with too many public attributes. We only check static definitions in a form of ``self.public = ...``. We do not count parent attributes. We do not count properties. We do not count annotations. We do not count class attributes. We do not count duplicates. Reasoning: Having too many public instance attributes means that your class is too complex in terms of coupling. Other classes and functions will rely on these concrete fields instead of better abstraction layers. Solution: Make some attributes protected. Split this class into several. If the class is a Data Transfer Object, then use ``@dataclass`` decorator. Configuration: This rule is configurable with ``--max-attributes``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_ATTRIBUTES` See also: https://en.wikipedia.org/wiki/Coupling_(computer_programming) .. versionadded:: 0.12.0 """ error_template = 'Found too many public instance attributes: {0}' code = 230
[docs]@final class CognitiveComplexityViolation(ASTViolation): """ Forbid functions with too much cognitive complexity. Reasoning: People are not great at reading and interpreting code in their heads. That's why code with a lot of nested loops, conditions, exceptions handlers, and context managers is hard to read and understand. Solution: Rewrite your code to be simpler. Use flat structures and conditions, remove nested loops. Configuration: This rule is configurable with ``--max-cognitive-score``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_COGNITIVE_SCORE` See also: https://en.wikipedia.org/wiki/Cognitive_complexity https://pypi.org/project/cognitive-complexity/ https://github.com/Melevir/flake8-cognitive-complexity .. versionadded:: 0.13.0 """ error_template = 'Found function with too much cognitive complexity: {0}' code = 231
[docs]@final class CognitiveModuleComplexityViolation(SimpleViolation): """ Forbid modules with average cognitive complexity that is too high. Reasoning: Modules with lots of functions might hide cognitive complexity inside many small and relatively simple functions. Solution: Rewrite your code to be simpler or use several modules. Configuration: This rule is configurable with ``--max-cognitive-average``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_COGNITIVE_AVERAGE` See also: https://en.wikipedia.org/wiki/Cognitive_complexity .. versionadded:: 0.13.0 """ error_template = 'Found module cognitive complexity that is too high: {0}' code = 232
[docs]@final class TooLongCallChainViolation(ASTViolation): """ Forbid call chains that are too long. Reasoning: Call chains that are too long are overcomplicated and indicators of bad API design. Solution: Split the expression into variables, functions or classes. Refactor the API to allow higher-level access to functions. Configuration: This rule is configurable with ``--max-call-level``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_CALL_LEVEL` .. versionadded:: 0.13.0 """ error_template = 'Found call chain that is too long: {0}' code = 233
[docs]@final class TooComplexAnnotationViolation(ASTViolation): """ Forbid overly complex annotations. Annotation complexity is maximum annotation nesting level. Example: ``List[int]`` has complexity of 2 and ``Tuple[List[Optional[str]], int]`` has complexity of 4. Reasoning: Overly complex annotations make your types unreadable. And make developers afraid of types. Solution: Create type aliases. And use them a lot! Configuration: This rule is configurable with ``--max-annotation-complexity``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_ANN_COMPLEXITY` See also: https://mypy.readthedocs.io/en/stable/kinds_of_types.html#type-aliases https://github.com/best-doctor/flake8-annotations-complexity .. versionadded:: 0.14.0 """ error_template = 'Found overly complex annotation: {0}' code = 234
[docs]@final class TooManyImportedModuleMembersViolation(ASTViolation): """ Forbid ``from ... import ...`` with too many imported names. Reasoning: Importing too many names from one import is an easy way to cause the violation ``WPS203`` - too many imported names. Solution: Refactor the imports to import a common namespace. Something like ``from package import module`` and then use it like ``module.function()``. Example:: # Correct: import module # 1 imported name # Wrong: from module import func1, func2, ..., funcN # N imported names Configuration: This rule is configurable with ``--max-import-from-members``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_IMPORT_FROM_MEMBERS` .. versionadded:: 0.15.0 """ error_template = 'Found too many imported names from a module: {0}' code = 235
[docs]@final class TooLongTupleUnpackViolation(ASTViolation): """ Forbid using too many variables to unpack a tuple. Reasoning: The order and meaning are hard to remember. Solution: If you have more than 2 values in a tuple, consider using ``typing.NamedTuple`` or a dataclass instead. Example:: # Correct: result = foo() # Wrong: a, b, c, d, e = foo() Configuration: This rule is configurable with ``--max-tuple-unpack-length``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_TUPLE_UNPACK_LENGTH` .. versionadded:: 0.15.0 """ error_template = 'Found too many variables used to unpack a tuple: {0}' code = 236
[docs]@final class TooComplexFormattedStringViolation(ASTViolation): """ Forbids ``f`` strings that are too complex. A complex format string is defined as use of any formatted value that is not: - the value of a variable - the value of a collection through lookup with a variable, number, or string as the key - the return value of a procedure call without arguments Related to :class:`~FormattedStringViolation`. Reasoning: Complex ``f`` strings are often difficult to understand, making the code less readable. Generally we don't allow ``f`` strings but this violation exists in case the user decides to ignore the general violation. Solution: Use ``.format()`` or assign complex expressions to variables before formatting. Example:: # Correct: f'smth {user.get_full_name()}' # Wrong: f'{reverse("url-name")}?{"&".join("user="+uid for uid in user_ids)}' .. versionadded:: 0.15.0 """ error_template = 'Found a too complex `f` string' code = 237
[docs]@final class TooManyRaisesViolation(ASTViolation): """ Forbids too many ``raise`` statements in a function. Reasoning: Too many ``raise`` statements in a function make the code untraceable and overcomplicated. Solution: Split the function into smaller functions, such that each of them can raise less errors. Create more standard errors, or use alternative ways to raise them. Configuration: This rule is configurable with ``--max-raises``. Default: :str:`wemake_python_styleguide.options.defaults.MAX_RAISES` .. versionadded:: 0.15.0 """ error_template = 'Found too many raises in a function: {0}' code = 238