scalar vs array and program control
Sebastian P. Luque
spluque at gmail.com
Sat Jul 25 11:30:58 EDT 2015
On Sat, 25 Jul 2015 14:44:43 +0200,
Laura Creighton <lac at openend.se> wrote:
> And because I was rushed and posted without revision I left out
> something important.
>> So this is, quite likely, the pattern that you are looking for:
>> try: all_your_code_which_is_happy_with_non_scalars except
>> WhateverErrorPythonGivesYouWhenYouTryThisWithScalars:
>> whatever_you_want_to_do_when_this_happens
>> This is the usual way to do things.
> I forgot to tell you that you are supposed to stick the try/except
> around the smallest chunk of code that you expect to get the
> exception.
> So you write this as
> code_you_expect_always_to_work more_code_you_expect_always_to_work
> try: these_four_lines_of_code_that_will_be_unhappy_if_its_a_scalar
> except ValueError: # whatever kind of error the real error is
> whatever_you_want_to_do_when_that_happens
> The reason is that if you get any Value Errors in the part of the code
> you always expect to work, then you don't want your program to run
> happily along running the code for 'its a scalar'. You don't want to
> hide real errors here.
> The other thing I forgot to mention is that sometimes you don't want
> to do anything but ignore any errors of this sort.
> Thats written like this:
> code_you_expect_always_to_work more_code_you_expect_always_to_work
> try: these_four_lines_of_code_that_will_be_unhappy_if_its_a_scalar
> except ValueError: pass # just ignore it
Thanks so much for all the pointers, and especially how `try` is used in
practice. Avoiding the tangle of checks for kind of input is precisely
what my intuition was telling me.
--
Seb
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