Add ordering constants: CMP_LT, CMP_EQ, CMP_GT

[hikari-no-yume]

This adds three constants to PHP:

const CMP_LT = -1;
const CMP_EQ = 0;
const CMP_GT = 1;

Why? Code readability. It means you can replace the magic numbers with more human-readable names, and prevent misunderstandings (particularly as to what strcmp($a, $b) === 0 does).

For example:

switch ($a <=> $b) {
    case CMP_LT:
        ...
    case CMP_EQ:
        ...
    case CMP_GT:
        ...
}

or

if (CMP_EQ === strcmp($a, $b)) {
    ...
}

[hikari-no-yume]

Ah, hmm, this doesn't work out. strcmp('a', 'c') is -2. Nevermind.

[rquadling]

It would be really nice to have CMP_LTZ, CMP_EQZ, CMP_GTZ, but this is a bit "macro-y".

Or, if you were feeling perverse, introduce three new callbacks for comparisons ...

strcmp($a, $b, callable $ltz, callable $eqz, callable $gtz)

But that is SO Javascript.

Introducing the spaceship operator is great, but you still have to do several comparisons against the result to do anything useful.

[hikari-no-yume]

Or just do <= 0 and >= 0

[datibbaw]

I suppose normalising all comparators to return only -1, 0 and 1 isn't going to happen any time soon? ;-)

[hikari-no-yume]

Probably not, someone must rely on it...

[hikari-no-yume]

Surprised me, though. I would've thought strcmp was normalised.