Know if a object member is a method

[Luca]

Hi all.

I think this is a newbie question... what is the best method to know
if a property of an object is a function?

I'm thinking something as

if type(obj.methodName)==???

Can someone help me?

--
-- luca

[Steven D'Aprano]

On Mon, 01 Sep 2008 10:43:25 +0200, Luca wrote:

Hi all.

I think this is a newbie question... what is the best method to know if
a property of an object is a function?

I'm thinking something as

if type(obj.methodName)==???

Can someone help me?

That's not quite as easy as you might think. In my testing, calling
type(obj.methodName) can give any of the following:

<type 'instancemethod'>
<type 'function'>
<type 'builtin_function_or_method'>
There may be others as well.

Possibly all you really need is to check if the attribute is callable
without caring what type of method or function it is:

>>callable(obj.methodName)

True

In my opinion, that's the best way.
If you are sure that the method won't have side-effects or bugs:

>>try:

.... obj.method()
.... except:
.... print "Not a method"
....

(But how can you be sure?)
If you insist on an explicit test, try this:

import new
type(obj.methodName) == new.instancemethod
or alternatively:

>>isinstance(obj.methodName, new.instancemethod)

True


--
Steven