63 lines
2.4 KiB
Plaintext
63 lines
2.4 KiB
Plaintext
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Instance methods, i.e. methods not annotated with <code>@cassmethod</code> or <code>@staticmethod</code>, are expected to have at least one parameter. This parameter will reference the object instance on which the method is called. By convention, this first parameter is named "self".
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Naming the "self" parameter differently is confusing. It might also indicate that the "self" parameter was forgotten, in which case calling the method will most probably fail.
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Note also that creating methods which are used as static methods without the <code>@staticmethod</code> decorator is a bad practice because calling these methods on an instance will raise a `TypeError`. Either move the method out of the class or decorate it with <code>@staticmethod</code>.
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This rule raises an issue when the first parameter of an instance method is not called "self".
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== Noncompliant Code Example
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----
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class MyClass:
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def send_request(request): # Noncompliant. "self" was probably forgotten
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print("send_request")
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class ClassWithStaticMethod:
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def static_method(param): # Noncompliant
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print(param)
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ClassWithStaticMethod().static_method(42) # Method is available on the instance but calling it will raise a TypeError
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----
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== Compliant Solution
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----
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class MyClass:
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def send_request(self, request):
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print("send_request")
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class ClassWithStaticMethod:
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@staticmethod
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def static_method(param):
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print(param)
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ClassWithStaticMethod().static_method(42)
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----
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== Exceptions
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This rule will also accept "cls" or "mcs" as first parameter's name for metaclasses' methods.
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No issue will be raised for methods called <code>\_\_init_subclass\_\_</code>, <code>\_\_class_getitem\_\_</code> or <code>\_\_new\_\_</code> as these methods' first parameter is a class.
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You can also disable issues on methods decorated with a specific decorator. Add these decorators to this rule's "ignoreDecorators" parameter.
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With "ignoredDecorators" set to "abstractmethod"
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----
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from abc import abstractmethod, ABC
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class MyClass(ABC):
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@abstractmethod
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def method(): # No issue, even if it is better in this case to also decorate with @staticmethod
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pass
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----
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== See
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* Python documentation - https://docs.python.org/3.8/tutorial/classes.html#method-objects[Method Objects]
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* PEP8 - https://www.python.org/dev/peps/pep-0008/#function-and-method-arguments[Function and Method Arguments]
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