On Fri, Apr 9, 2021, 3:23 PM Peter Ludemann <peter.ludem...@gmail.com>
wrote:
> David Mertz wrote:
> > The pattern of "Create an empty collection, then add stuff in a loop" is
> quite common, ...
>
> Or you can use comprehensions, in which case there's no need for creating
> an empty collection.
>
> s = {f(x) for x in some_list}
>
Only for the very simplest cases of that pattern. Of course I use
comprehensions in such cases.
In many other cases, the loop that adds stuff to collections also has
conditional branches to add this vs that, calls to other functions to get
more data or make decisions, nested loops, temporary variables,
side-effects, and so on.
... Yes, of course with enough contortions, some of that can be worked into
comprehensions. But usually it is better not to, and sometimes it is
impossible.
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