Hi Guys, I had a question regarding:
> On the other hand, if you have `for i, v := range a {` then the
> expression *is* evaluated before the start of the loop.
I have a code (https://goplay.tools/snippet/dMwD0_rEhkB) where I am ranging
over a slice, and updating (removing the zeroth element form the same slice
being ranged over) here I see that the "i" values is not being
re-evaluated, it just gives an increasing number even if the ranged over
slice has changed . Which can also be seen when I am printing the ith
element given to me by the range, and the receiving out of range panic
On Saturday, March 19, 2022 at 2:01:27 AM UTC+5:30 Dan Kortschak wrote:
> On Fri, 2022-03-18 at 16:53 +0100, 'Axel Wagner' via golang-nuts wrote:
> > One thing to keep in mind is that Go development was incremental and
> > was done, from early on, by having multiple implementations.
> > Incremental processes often lead to different results than designing
> > a language from a blank slate. Ambiguities in the spec are often
> > discovered only when someone notices that implementations disagree
> > and must be resolved somehow. Sometimes that happens after Go 1 and
> > the resolution must happen in a way that, as much as possible,
> > retains stability guarantees. So, it's not unsurprising if we get
> > non-obvious spec clauses such as this.
> >
> > Specifically, I can well imagine that this particular case arose,
> > because it was discovered after the fact that one implementation
> > contained an optimization to not evaluate the argument to `len`,
> > while the other didn't and the question of side-effects only arose
> > when someone noticed.
> >
> > I don't really know the answer to your question. I can't think of
> > anything which would break. That being said, I also don't think it's
> > something that really needs "fixing", as it seems a pretty uncommon
> > concern.
>
> There is some discussion on the reasons when the original narrowing of
> the behaviour was introduced (https://codereview.appspot.com/4444050).
>
> It's actually quite an interesting spec change from a language history
> perspective, more because of the chan discussion than this particular
> issue.
>
>
>
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