[RFC] Add support for dynamic variable names in function scope

[haskellcamargo]

This pull-requests adds the support for dynamic variable names using strings on the scope of functions without the necessity of using global.

This would fail with a syntactic error before:

${'+'} = function ($x, $y) { return $x + $y; };

$test_add = (function ($a, $b) use (${'+'}) {
  return ${'+'}($a, $b);
})(10, 20);

echo $test_add;

The name ${'+'} wouldn't be be accessible without declaring it using the global keyword or using an alias.

The support for dynamic items has been added only for literal strings T_CONSTANT_ENCAPSED_STRING because we would have to evaluate the expression and then import the name without having a direct reference to the variable for variable variables, such as use ($$test). Well, I'll try to open a RFC to solve this a posteriori. I'm also planning to open a RFC to support aliases in function use, such as function () use (${'+'} as $plus) {} in order to preserve scope.

I have also implemented support for references to these variables:

${'+'} = 10;
(function () use (&${'+'}) {
  ${'+'} = 20;
})();
echo ${'+'}; // 20

[nikic]

Is there an RFC coming for this? I don't think this can go through as a "bug fix"...

If we're going to support this here, there's a bunch of other places that currently only support simple variables, in particular catch clauses, function parameters and static variables. Should we support ${} syntax there as well? If not, where do we draw the line?

[haskellcamargo]

Well, I believe we can expose our arguments better in a RFC. However, I'll need to get karma for that. I've mailed internals mail list last year and got no answer. Could you check it, please?

[nikic]

Do you have a link to your mail handy?

[haskellcamargo]

Do you mean my e-mail? marcelocamargo@linuxmail.org. My user on php.net is haskellcamargo.

[nikic]

You mentioned that you mailed internals last year for RFC karma, but I couldn't find the mail. In any case I can't give out karma anyway, maybe @Tyrael can look into it?

[onlurking]

No update on this yet?

[marcioAlmada]

/pings @Tyrael again 😄

[haskellcamargo]

This PR has almost 6 months. :')
The little baby is growing and becoming a lil' child 🎉 🎉 🎉
I'll make a party when it reaches 1 year!

[marcioAlmada]

@haskellcamargo It seems your request got lost in the pipelines (this happened to my first attempt). How about asking for RFC karma again on internals? Or try the IRC channel, it's faster there.

[onlurking]

Sadly, no reponse yet, i'd love to see at least some feedback on this one.

[sgolemon]

I sent a ping on list http://news.php.net/php.internals/98604

In the mean time, how about a gist based RFC? It'll get the conversation started.

[bjori]

heh. I don't know what happened to all the wiki admins.
I've added you (haskellcamargo) to the rfc group.

[cmb69]

@haskellcamargo Are you still interested in this feature? If so, please start the RFC process (I can confirm that the Wiki user haskellcamargo has RFC karma).

[cmb69]

@haskellcamargo ping!

[cmb69]

Since there has been no progress for quite some time, I'm closing this PR. Please re-open, if an RFC is available.