[Python-ideas] Going off-topic (was: Null coalescing operator)

[Brett Cannon]

On Wed, 2 Nov 2016 at 17:34 Mikhail V <mikhailwas at gmail.com> wrote:

> On 2 November 2016 at 21:50, David Mertz <mertz at gnosis.cx> wrote:
> > Even though I really don't want new null-coalescing operators, I really
> > appreciate the ternary operator in Python (or in C).
> >
> > On Wed, Nov 2, 2016 at 12:38 PM, Mikhail V <mikhailwas at gmail.com> wrote:
> >>
> >> result = a > b ? x : y
> >>
> >> is IMHO a syntactical herecy. Such things disgust me from programming.
> >> Why on earth one cannot just wrap it in function
> >> c = nicefunc(a,b)
> >
> >
> > The problem here is that the general form isn't ONLY to return 'x' or 'y'
> > but the decide between arbitrary values.  Hard-coding the variables into
> the
> > function loses 90%+ of the point.
> >
> > So the general function would need a signature like:
> >
> >     c = nicefunc(a, b, x, y)
> >
> > The problem here is that this call might be:
> >
> >     c = nicefunc(a, b, run_for_hours(), has_side_effects())
> >
> > We only want ONE of 'x' and 'y' to eagerly evaluate.  In the C or Python
> > ternary we get exactly that.  Obviously, that also happens in your fully
> > spelled out if/else block too, but that's multiline and needs to setup
> > variables not just be used as an expression.
>
> [Apologies for off-topic one more time]
>

A quick mailing list etiquette lesson: if you know you're going off-topic
then please start a new thread with a new subject line (see the subject
line for this new thread as an example). Since "off-topic" means "new
thread of discussion", then please just start a new thread. You can't
assume that people are reading email through an email client which does
threading, meaning those of us not interested in the off-topic offshoot
have to read your email, realize it's off-topic, and then get passed that
email to get to the next email that is on-topic (and this is still a time
sink even when your first line of your reply is "this is off-topic").

So please be mindful of when you stray off-topic, and when you do then
start a new thread to make managing different discussions easier for
everyone.
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