Re: returning True, False or None

[Steve Holden]

Steven Bethard wrote:
I have lists containing values that are all either True, False or None, 
e.g.:

    [True,  None,  None,  False]
    [None,  False, False, None ]
    [False, True,  True,  True ]
    etc.
For a given list:
* If all values are None, the function should return None.
* If at least one value is True, the function should return True.
* Otherwise, the function should return False.
Right now, my code looks like:
    if True in lst:
        return True
    elif False in lst:
        return False
    else:
        return None
This has a light code smell for me though -- can anyone see a simpler 
way of writing this?

STeVe
That code looks like a pretty solid implementation of the spec to me. 
There isn't a strict need for the last else, of course, which may be the 
smell you detect.

If you wanted to get clever you could write something like
for i in True, False:
  if i in lst:
    return i
return False
but frankly I think that's more obscure, and saves you pretty much nothing.
regards
 Steve
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