2.3.9.4 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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