On Sun, May 24, 2020 at 01:38:26PM -0400, David Mertz wrote:
> The pattern:
>
> def fun(..., option=None):
> if option is None:
> option = something_else
>
> Becomes second nature very quickly. Once you learn it, you know it. A
> line of two of code isn't a big deal.
Sure, but when you have seven parameters that all take late-bound
defaults, it becomes a PITA.
def func(...):
# late binding boilerplate
if dopey is None:
if happy is None:
if doc is None:
if sneezy is None:
if grumpy is None:
if sleepy is None:
if bashful is None:
# AAAAND at last we get to the actual function body...
This "if arg is None..." idiom is okay, but it's just a tiny bit of
extra friction when coding. Nothing as drastic as a "design flaw"
or a "wart" on the language, but it's slightly rough edge.
> But this discussion DOES remind me of something much more general that I've
> wanted for a long time, and that has had long discussion threads at various
> times. A general `deferred` or `delayed` (or other spellign) construct for
> language-wide delayed computation would be cool. It would also require
> rethinking a whole lot of corners. I think it would address this mutable
> default, but it would also do a thousand other useful things.
Well, I don't know about a thousand, but I'm currently writing up a
proto-PEP for delayed evaluation, and I've got six use-cases so far.
--
Steven
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