Coding style

[Carl Banks]

Peter Otten wrote:
> Carl Banks wrote:
>
> >     def process_values(lst):
> >         if not lst:
> >             return
> >         do_expensive_initialization_step()
> >         for item in lst:
> >             do_something_with(item)
> >         do_expensive_finalization_step()
>
> > What if you called the function like this:
> >
> >     process_values(x.strip() for x in values_lst)
> >
> > Oops, now we've just gone through an expensive initialization and
> > finalization for nothing (since values_lst was empty).  Maybe some
> > subtle bugs introduced.  If we're lucky, the finalization step will
> > throw an exception.
>
> The good news is that the above has a 99 percent chance that it just works
> with iterators/generators -- even though the writer may not have been aware
> of them/they didn't exist when the code was written...

There's a litmus test I like to use when justifying something with
percentages: I imagine that I'm presenting it to my boss, and ask
myself if I still expect to have a job the next day. :-)

Yes, I agree with you, it most cases I expect merely unnecessary work.
(Which is not the best news; the best news would be an exception right
away.)  That's why I think this is only a "pretty good" reason to use
"if len(lst)>0", not a slam dunk.


Carl Banks