Python gurus are going to laugh at me for this one but I learnt it today; how to check if an object is callable. Before this I thought I was clever with this:

>>> def foo(): return "s"
>>> hasattr(foo, '__call__')
True
>>> hasattr(foo(), '__call__')
False

But there was an easier way. I discovered this by accident and looked it up in the documentation after. Use the builtin function called 'callable()':

>>> def foo(): return "s"
>>> callable(foo)
True
>>> callable(foo())
False

D'oh!

James Gray - 03 April 2005 [«« Reply to this]
According to PEP 3000 the callable built-in function is going to be gone in Python 3.0. In the interest of staying compatible you may want to stick with the old way or call it and catch the exception as the previous comment mentioned. (PEP 3000 - http://www.python.org/peps/pep-3000.html)

Often it pays not to get fancy...
Anonymous - 03 April 2005 [«« Reply to this]
probably the best way (if you can afford to wait until the last possible moment) is to try making the call and catch the TypeError exception
Peter Bengtsson - 03 April 2005 [«« Reply to this]
I prefer not to use try and except statements. They look too wild and don't give any performance improvement.
Anonymous - 15 September 2008 [«« Reply to this]
Except for callables which might trigger nuclear weapons.
Eeswar Ravi - 10 January 2009 [«« Reply to this]
Good discovery. It helped you.

I tried callable(iter) and callable(candygram.link)

both returned true.....ya I was lazy to write a callable.
Anonymous - 29 July 2009 [«« Reply to this]
"the callable built-in function is going to be gone in Python 3.0"

in that case, hasattr(foo, '__call__') seems more logical (to a second hand reader) than catching the exception, in my opinion..
Me Me Me - 29 November 2012 [«« Reply to this]
Python 3.3 shell log:

>>> def Foo():
return Foo

>>> f = Foo()
>>> f
<function Foo at 0x01F45930>
>>> callable(Foo)
True
>>> callable(Foo())
True
>>> callable(f)
True
Peter Bengtsson - 29 November 2012 [«« Reply to this]
Is that not what you expect?


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