Steven D'Aprano <st...@remove-this-cybersource.com.au> writes:
> >> Not everything needs to be a one liner. If you need this, do it the
> >> old- fashioned way:
> >>
> >> t = foo()
> >> if not pred(t): t = default_value
> >
> > I already explained how to write it as a one-liner:
> >
> > t = (lambda y: y if pred(y) else default_value)(foo())
>
> I didn't say it couldn't be written as a one-liner. I suggested that it
> was better not to.
Ahh. I misunderstood the first sentence above as dismissing the
possibility. Sorry. I agree that it's not a /nice/ one-liner. ;-)
> The costs of the one-liner are:
>
> * reduced readability;
> * requires an increased level of knowledge of the reader ("what's lambda
> do?");
> * runtime inefficiency (you create a function object, only to use it once
> then throw it away).
This last can be obviated by a clever compiler (which, in our case, we
have not got). The second could be considered an advantage: it's
educational!
> The advantages?
>
> * one fewer line of code.
>
> In my experience, the obsessiveness in which some people look for one-
> liners is far from helpful, and goes against the spirit of Python. This
> isn't Perl :)
Oh, I agree completely. On the other hand, it's just /fun/. Python is
a fun language and using its features in playfully unusual ways is
enjoyable; like a good pun in a natural language. Just as puns aren't
always appropriate in written language, playful code isn't always
appropriate either; but that doesn't mean it's never appropriate.
(Java has no sense of humour. C++ does have, but it's a bit weird.)
-- [mdw]
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