Asssociative Array by Key-Value-Pair

[H. S. Teoh via Digitalmars-d-learn]

On Tue, Dec 16, 2014 at 11:56:20AM -0500, Steven Schveighoffer via Digitalmars-d-learn wrote:
> On 12/16/14 11:47 AM, "Nordlöw" wrote:
> >On Tuesday, 16 December 2014 at 16:08:09 UTC, Steven Schveighoffer wrote:
> >>I can never ever see a reason to implement 2 different ways to
> >>traverse the elements, just to piss off people?
> >>
> >>If you make a PR that adds that to documentation, I will pull it if it
> >>makes you feel better. I don't think it hurts, but don't think it's
> >>worth my time to make such a PR.
> >>
> >>-Steve
> >
> >I can do PR for adding
> >
> >https://github.com/nordlow/justd/blob/master/range_ex.d#L527
> >
> >to Phobos.
> >
> >Were should I put it/them?
> 
> I think to be clear, the PR I said I will pull is for the
> documentation update. A doc change has no effect on the code.
> 
> I will certainly review one that adds iteration of both key and value
> (as that is pretty much a free addition given the existing code), but
> it will have to go through normal review process.
> 
> Note, the range you have referenced would not be accepted as it
> requires an unnecessary AA lookup for the value, and it requires
> access to phobos (this should be added to druntime). Take a look at
> object.di and see how the byKey and byValue ranges work. It would be
> trivial to add a byPair range (don't really like that name). The large
> controversy is regarding how it returns the "front" element.
> 
> It would have to satisfy 3 requirements I think:
> 
> 1. I should be able to do foreach(k, v; r) on it.
> 2. I should be able to access both key and value separately for each
> element.
> 3. It cannot depend on phobos.
[...]

This has already been implemented, btw, but it was rejected because it
did not use Phobos' Tuple type for .front. The code is here:

	https://github.com/D-Programming-Language/druntime/pull/574

One possibility is that we resurrect this PR and also add a new Phobos
PR that wraps around .front to return Tuple instead (perhaps also rename
byPair to something else in the process).


T

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