[Python-Dev] for...else

[Koos Zevenhoven]

On Mon, Jul 24, 2017 at 7:14 PM, Steven D'Aprano <steve at pearwood.info>
wrote:

> Hello Kiuhnm, and welcome.
>
> On Mon, Jul 24, 2017 at 05:35:03PM +0200, Kiuhnm via Python-Dev wrote:
> > Hello,
> >
> > I think that the expression "for...else" or "while...else" is completely
> > counter-intuitive.
>
>
> You may be right -- this has been discussed many, many times before. In
> my personal opinion, the best (and only accurate!) phrase would have
> been:
>
> for item in sequence:
>     # block
> then:
>     # block
>
>
​IMO,

for item in sequence:
    # block
nobreak:   # or perhaps `if not break:`
    # block

would be clearer (if the syntax is necessary at all).


​[...]


> ​
>
> > Wouldn't it be possible to make it clearer? Maybe
> > something like
>
> At this point, no, it is not practical to change the syntax used. Maybe
> when Python 3.0 was first introduced, but that ship has long sailed. It
> is very, very unlikely that the syntax for this will ever change, but if
> it does, it probably won't be until something in the distant future like
> Python 5.
>

​I don't have a strong opinion on this particular case, but if something
like this is changed in Python 5, I think the decision should be made much
earlier (now?) so that the old else syntax could be discouraged (and new
syntax potentially already introduced). The same thing would apply to many
other "possibly in Python 5" changes, where there is no reason to expect
that the situation is somehow different years later.

-- Koos


>
> But not Python 4: Guido has already ruled that Python 4 will not include
> major backwards-incompatible changes. Going from 3 to 4 will not be as
> disruptive as going from 2 to 3.
>
>
​[...]​


-- 
+ Koos Zevenhoven + http://twitter.com/k7hoven +
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