instance method questions

[Peter Otten]

Danny wrote:

> I have created an instance method for an object using new.instancemethod.
> It works great. Now the questions are:
> 
> 1) how do I dynamically inspect an object to determine if it has an
> instance method? (there is a class method with the same name)

Why would you want to do that?

Here is a way that relies on an implementation detail of current CPython:

>>> class Foo(object):
...     def foo(self): pass
...     def __init__(self):
...             import new
...             def bar(self): pass
...             self.foo = new.instancemethod(bar, self)
...
>>> x = Foo()
>>> x.foo is x.foo
True
>>> del x.foo
>>> x.foo is x.foo
False

This alternative is a little less subtle:

>>> y = Foo()
>>> "foo" in y.__dict__
True
>>> del y.foo
>>> "foo" in y.__dict__
False

Peter