3.11.4 Methods
Methods are functions that are called using the attribute notation. There are two flavors: built-in methods (such as append() on lists) and class instance methods. Built-in methods are described with the types that support them.
The implementation adds two special read-only attributes to class
instance methods: m.im_self is the object on which the
method operates, and m.im_func is the function
implementing the method. Calling m(arg-1,
arg-2, ..., arg-n) is completely equivalent to
calling m.im_func(m.im_self, arg-1,
arg-2, ..., arg-n).
Class instance methods are either bound or unbound,
referring to whether the method was accessed through an instance or a
class, respectively. When a method is unbound, its im_self
attribute will be None and if called, an explicit self
object must be passed as the first argument. In this case,
self must be an instance of the unbound method's class (or a
subclass of that class), otherwise a TypeError is raised.
Like function objects, methods objects support getting
arbitrary attributes. However, since method attributes are actually
stored on the underlying function object (meth.im_func),
setting method attributes on either bound or unbound methods is
disallowed. Attempting to set a method attribute results in a
TypeError being raised. In order to set a method attribute,
you need to explicitly set it on the underlying function object:
class C:
def method(self):
pass
c = C()
c.method.im_func.whoami = 'my name is c'
See the Python Reference Manual for more information.
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Release 2.5, documentation updated on 19th September, 2006.