[Tutor] question about strip() and list comprehension

[Jared Nielsen]

Thanks Danny!
That was an awesome explanation.


On Tue, Apr 8, 2014 at 7:05 PM, Danny Yoo <dyoo at hashcollision.org> wrote:

>
>> if line.strip()
>>
>> Is that stripping the line of white space at the same time that it is
>> testing it?
>>
>>
>
> Two features about Python:
>
> 1.  Strings are immutable, so the above is computing what a
> whitespace-stripped line would look like.  So that means that
> 'line.strip()' is doing just a computation: it's not mutating the original
> line, but computing a new string that has its leading and trailing
> whitespace stripped away.
>
>
> 2.  Empty strings are treated as false values.  I'm not happy with how
> loose Python treats truth, and would rather prefer:
>
>     if line.strip() != "": ...
>
> so that the thing being tested is explicitly either True or False.  I like
> my truth to be black and white, but I suppose I'll have to grimace and bear
> the fuzziness.  :P
>
>
> Together, we see those two features allow us to look at the test in the
> Python code:
>
>    if line.strip(): ...
>
> and rephrase it in English as:
>
>    "If the line consists of at least one non-whitespace character: ..."
>



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