02 April 2005 8 comments Python
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!
Often it pays not to get fancy...
I tried callable(iter) and callable(candygram.link)
both returned true.....ya I was lazy to write a callable.
in that case, hasattr(foo, '__call__') seems more logical (to a second hand reader) than catching the exception, in my opinion..
>>> def Foo():
return Foo
>>> f = Foo()
>>> f
<function Foo at 0x01F45930>
>>> callable(Foo)
True
>>> callable(Foo())
True
>>> callable(f)
True