On Fri, 17 Jul 2009 00:34:00 -0700, Paul Rubin wrote:
> Steven D'Aprano <st...@remove-this-cybersource.com.au> writes:
>> It is very useful to be able to write e.g.:
>>
>> if header or body or footer:
>> print assemble_page(header, body, footer)
>>
>> and have empty strings to be equivalent to False.
>
> Why doesn't assemble_page properly handle the case where header, body,
> and footer are all empty? That would let you eliminate the if. "Make
> sure your code 'does nothing' gracefully" (Kernighan and Plauger).
You mean something like this?
def assemble_page(header, body, footer):
if header or body or footer:
do_lots_of_expensive_processing()
else:
do_nothing_gracefully()
Sure, why not?
Whatever way you do it, my point is that it is very useful to perform
branching tests on non-Boolean objects. Wherever you put the test, being
able to write:
if header or body or footer:
is a huge improvement over:
if (header != '') or (body != '') or (footer != ''):
--
Steven
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