Python之——@staticmethod和@classmet

@staticmethod

@staticmethod
Transform a method into a static method.

A static method does not receive an implicit first argument. To declare a static method, use this idiom:

class C:
@staticmethod
def f(arg1, arg2, ...): ...
The @staticmethod form is a function decorator – see the description of function definitions in Function definitions for details.

It can be called either on the class (such as C.f()) or on an instance (such as C().f()). The instance is ignored except for its class.

Static methods in Python are similar to those found in Java or C++. Also see classmethod() for a variant that is useful for creating alternate class constructors.

Like all decorators, it is also possible to call staticmethod as a regular function and do something with its result. This is needed in some cases where you need a reference to a function from a class body and you want to avoid the automatic transformation to instance method. For these cases, use this idiom:

class C:
builtin_open = staticmethod(open)
For more information on static methods, consult the documentation on the standard type hierarchy in The standard type hierarchy.

class str(object='')
class str(object=b'', encoding='utf-8', errors='strict')
Return a str version of object. See str() for details.

str is the built-in string class. For general information about strings, see Text Sequence Type — str.

@classmethod

@classmethod
Transform a method into a class method.

A class method receives the class as implicit first argument, just like an instance method receives the instance. To declare a class method, use this idiom:

class C:
@classmethod
def f(cls, arg1, arg2, ...): ...
The @classmethod form is a function decorator – see the description of function definitions in Function definitions for details.

It can be called either on the class (such as C.f()) or on an instance (such as C().f()). The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument.

Class methods are different than C++ or Java static methods. If you want those, see staticmethod() in this section.

For more information on class methods, consult the documentation on the standard type hierarchy in The standard type hierarchy.