[Tutor] Help me Be Pythonic [logic and readability]

[Danny Yoo]

On Tue, 28 May 2002, Sean 'Shaleh' Perry wrote:


> > The reason for this is because find()  will return -1 if it can't find
> > the string we're looking for.  For example, if we play around with
> > find() in the interactive interpreter:
> >
>
> so why not do:
>
>
> if find() != -1?

Hi Sean,


This also works well.  Since find() returns either '-1' if it can't find
the target string, or something else (the position) if it does find
something, we can compose the logic in several ways that'll work.



I feel that the important part is to be consistant; it would probably not
be a good thing to do it one way, and then switch over to the other, at
least, not without good reasons.  What I mean is that something like:

###
for url in fileinput.input():
    if url.find('.com') >= 0: print "success"
    else: print "unavailable"

    if url.find('.org') != -1: print "success"
    else: print "unavailable"
###

would look a little off to me.  Even though the logic is impeccable, the
different process toward getting at it is somewhat jarring, at least to my
eyes.



Even "worse" from a (subjective) consistancy standpoint might be:

###
for url in fileinput.input():
    if url.find('.com') >= 0: print "success"
    else: print "unavailable"

    if url.find('.org') == -1: print "unavailable"
    else: print "success"
###

... Although it does have a certain... symmetry to it... still, I don't
like it!  It just feels like it... "bounces" to me, in a way that it
doesn't need to.  At least in Python, I like code to flow quietly.  These
are purely subjective, irrational terms, but that's just how it feels to
me.  *grin*


Talk to you later!