access to global scope from functions

[allain]

Given the following JavaScript the PHP generated was malformed:

const total = 0
function add(x) {
  total += x
}

Produced this PHP:

$total = 0;
function add($x) use (&$total) {
$total += $x;
}

Unfortunately use is not allowed to be used on FunctionDeclarations anything other than an so to make the above work I've made FunctionDeclarations use the global keyword instead:

$total = 0;
function add($x) {
global $total;
$total += $x;
}

At the same time I found a bug with function expressions, as opposed to Arrow Functions that produced the wrong code too. Those now use the use keyword too.

[allain]

I'm pretty sure isn't a good solution. I mean, it produces valid PHP code, but it's not semantically correct.

The following code when run in JS yields hello for example, but would print nothing in PHP.

function a(message) {
  function b() {
    print(message)
  }
  b()
}
a('Hello');

I think if we want PHP interop still (functions defined in JS to be available in PHP) we'll need to transform all nested FunctionDeclarations into FunctionExpressions, prior to generating the PHP

[endel]

Hi @allain, sorry the huge delay to answer here. I wasn't receiving email updates from this repository. Thanks a lot for your time creating this pull-request!

I've just noticed that this problem is quite complex, actually. Even the use (&$total) transformation doesn't work properly when using an AssignmentExpression inside a function block.

JavaScript input:

const total = 0;
function add(x) {
  total += x;
}

PHP output:

$total = 0;
function add($x) {
$total += $x;
}

The problem is that - as functions does create a new scope - when using assignments, the transformation tool assumes immediatelly that it should be assigned as a new variable in the current scope, and not re-used from a previous scope.

A silly workaround for that would be to access the variable first, but that's really odd.

JavaScript input (with workaround)

const total = 0;
function add(x) {
  total
  total += x;
}

PHP output (with correct use)

$total = 0;
function add($x) use (&$total) {
$total;
$total += $x;
}

I understand your proposal here is to allow calling global for these variables, but they're not being added to the scope's using list first, so even if I accept your pull-request, things won't work properly.

[allain]

I agree. Odd and working is fine I suppose, are you just proposing to leave well enough alone?

[endel]

Does this happen only when functions are on the higher scope? I've just pushed an update that should fix on that case!

Let me know if that works for you!

[endel]

Added this test case: https://github.com/endel/js2php/blob/master/test/fixtures/failures.js