python 方法窃取器

Question

如何从一个类“窃取”或复制一个方法到另一个类？

示例代码:

class A(object):
  def foo(self):
    print "blah"


class B(object):
  foo = A.foo

B().foo()

预期输出:

"blah"

相反:

TypeError: unbound method foo() must be called with A instance as first argument (got nothing instead)

Answer 1

使用__func__:

>>> A.foo
<unbound method A.foo>
>>> A.foo.__func__
<function foo at 0x00BC5F70>
>>> class B(object):
...   foo = A.foo.__func__
...
>>> B().foo()
"blah"

引用 the docs :

An instance method object combines a class, a class instance and any callable object (normally a user-defined function).

Special read-only attributes: __self__ is the class instance object, __func__ is the function object; __doc__ is the method’s documentation (same as __func__.__doc__); __name__ is the method name (same as __func__.__name__); __module__ is the name of the module the method was defined in, or None if unavailable.