create boolean

Grant Edwards grante at visi.com
Mon Mar 9 00:48:32 CET 2009


On 2009-03-08, Rhodri James <rhodri at wildebst.demon.co.uk> wrote:
>>>>
>>>>   b = (n is not None) and (n != [])
>>>
>>> The second comparison isn't actually necessary, since an
>>> empty list is True and a non-empty one False.
>>>
>>>    b = (n is not None) and n
>>>
>>> Putting the comparison in does make the code slightly less
>>> "magic", though, so it's not a bad idea to do it!
>>
>> Putting in the second comparison in makes the code match the
>> stated requirement.  Otherwise you have to start making
>> assumptions about what n might be besides None or the empty
>> list.
>
> The OP stated that we *could* assume that n was None or a
> list, so I stand by what I said.

I didn't say that he hadn't authorized that assumption.  I just
said that the code does rely on such an assumption.  In my
experience, assumptions like that result broken code down the
road.

-- 
Grant




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