Proposal: Dump circular references in var_export() using IIFE

[carlosmintfan]

Proposal: Dump circular references in var_export() using IIFE

[iluuu1994]

var_export() doesn't really support references to begin with. E.g:

$a = ['foo'];
$b = [&$a, &$a];
var_export($b);

Results in:

array (
  0 => 
  array (
    0 => 'foo',
  ),
  1 => 
  array (
    0 => 'foo',
  ),
)

Honestly, I'm not sure supporting recursive arrays is a worthwhile goal. Recursive arrays are a foot gun, because many things can trigger fatal errors. E.g.:

$a = [&$a];
var_dump($a === [[]]);

Can you clarify what your use-case is?

[iluuu1994]

@carlosmintfan Thank you for clarifying! In that case, I'd honestly prefer closing this as a #wontfix until we know why we're doing it. But I'll keep this open for a few days for others to chime in.

[carlosmintfan]

I don't really have a practical use case for it. This was just an idea how it could be implemented theoretically. :)

[carlosmintfan]

$a = [&$a];
var_dump($a === [[]]);

Oh wow, why doesn't this just eval to false?

[iluuu1994]

In this case, we probably could. But encountering recursive elements doesn't necessarily mean the elements are not equal. For example:

$a = [&$a];
$b = [[&$b]];
$a === $b;

These arrays should be equal, but understanding they are equal can get quite tricky. While we could probably find a solution for this but it might impact performance of comparison overall, which would not be a good trade-off IMO. I'm not exactly sure why we're not just throwing an Error, instead of a fatal error. I'll have a look at that.

[carlosmintfan]

In this case, we probably could. But encountering recursive elements doesn't necessarily mean the elements are not equal. For example:

$a = [&$a];

$b = [[&$b]];

$a === $b;

These arrays should be equal, but understanding they are equal can get quite tricky. While we could probably find a solution for this but it might impact performance of comparison overall, which would not be a good trade-off IMO. I'm not exactly sure why we're not just throwing an Error, instead of a fatal error. I'll have a look at that.

LOL, yeah $var = [&$var] is theoretically the same as $var = [[&$var]] cause Infinity + 1 stays Infinity, but I guess var_dumping them, the output will be different. I'll try it later today.

[carlosmintfan]

So yeah,

php > $a = [&$a];
php > $b = [[&$b]];
php > var_dump($a);
array(1) {
  [0]=>
  *RECURSION*
}
php > var_dump($b);
array(1) {
  [0]=>
  array(1) {
    [0]=>
    *RECURSION*
  }
}
php >

Hmm, yeah, but it's all theory for me, I don't use this anyway, at least until now. 😄