Ranges and indexes with foreach

[bearophile]

Jonathan M Davis:

> The lack of indexing for foreach and ranges is a bit of problem (not a huge 
> one but definitely an annoying one - it's one of the few reasons to still use 
> opApply instead of ranges). The obvious solution is to just have the compiler 
> provide a counter.
> ...
> Thoughts? Is there anything obvious (or non-obvious) that I'm missing here?

Time ago I have proposed this, I think this is a tidier solution, that requires no compiler changes:
http://d.puremagic.com/issues/show_bug.cgi?id=5550

(and then the front-end is free to recognize the usage of this Phobos range enumerate(), and optimize it much better).

Usage example (this also uses the tuple unpacking syntax):

foreach ((i, e); enumerate(range)) {
    // code that uses i and e
}


Until the tuple unpacking syntax is not present you use:

foreach (ie; enumerate(range)) {
    const i = ie[0];
    const e = ie[1];
    // code that uses i and e
}

Bye,
bearophile