Re: returning True, False or None

[Brian van den Broek]

Alex Martelli said unto the world upon 2005-02-04 13:02:
Steven Bethard <[EMAIL PROTECTED]> 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:
<SNIP OP's code>
This has a light code smell for me though -- can anyone see a simpler
way of writing this?

What about...:
for val in lst:
    if val is not None:
        return val
return None
or the somewhat fancy/clever:
for val in (x for x in lst if x is not None):
    return val
return None
Alex
These don't do what the OP desired.
.>>> test_case = [False, True,  True,  True ]
.>>> def alexs_funct(lst):
.        for val in lst:
.            if val is not None:
.                return val
.        return None
>>> alexs_funct(test_case)
False
But, by the 'spec', it ought return True.
Best,
Brian vdB
A mere newbie, quite pleased with himself for finding a problem with 
'bot code -- next scheduled to occur mid 2011 :-)

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