Named anonymous functions

[divinity76]

Description

Javascript support naming anonymous functions, letting the function refer to itself for recursion without polluting the surrounding scope. And it provides better stack traces. For example:

function f(cb) {
    console.log(cb.name); // Output: "funName"
    cb(0);
}

f(function funName(i) {
    // funName is available here
    if (i < 3) {
        console.log(i);
        funName(i + 1);
    }
});
// funName is not available here.

outputting

funName
0
1
2

Would be nice if PHP could support it too. Like

function d(callable $arg) {
    $ref = new ReflectionFunction($arg);
    $name = $ref->getName();
    var_dump($name);
    $arg(0);
}

d(function funName(int $i) {
    if ($i < 3) {
        echo $i, "\n";
        funName($i + 1);
    }
});
// funName is not available here.

printing

string(7) "funName"
0
1
2

Benefits:

• Simplified Recursion: Enables recursive anonymous functions without needing workarounds like use (&$funName) or relying on debug_backtrace() hacks.
• Improved Debugging: Stack traces and error messages involving anonymous functions could show meaningful names instead of just "{closure}"
• Enhanced Metadata Support: When exporting function metadata (for instance, in APIs like OpenAI's ChatGPT tools API), a named anonymous function's name could be deduced automatically via reflection, rather than having to explicitly specify "string $functionName" (already possible if anonymous functions are simply not supported, though)

[Girgias]

Since 8.4 closures have better names than just "{closure}" as they refer to the file name, and line number where the closure has been defined. Moreover, closures from "real" functions, already have descriptive names. See https://3v4l.org/lJmX8.

This feature really seems just strange to me, I don't know how likely recursive anonymous functions are, and even then just improving the behaviour of the __FUNCTION__ magic constant seems like a better plan.

[TimWolla]

as they refer to the file name, and line number where the closure has been defined

More specifically: They refer to the parent function + line number. Only top-level closures refer to the filename (because the file effectively is the parent function).

see https://github.com/php/php-src/blob/master/Zend/tests/closures/closure_065.phpt

[TimWolla]

And for the proposal at hand, there is this RFC: https://wiki.php.net/rfc/closure_self_reference

[divinity76]

Since 8.4 closures have better names than just "{closure}" as they refer to the file name, and line number where the closure has been defined.

nice.

this RFC: https://wiki.php.net/rfc/closure_self_reference

nice. closing.

[iluuu1994]

This feature really seems just strange to me, I don't know how likely recursive anonymous functions are, and even then just improving the behaviour of the FUNCTION magic constant seems like a better plan.

Closures also carry context through captured variables, so __FUNCTION__ is not a viable alternative. __CLOSURE__ might work, evaluating to ZEND_CLOSURE_OBJECT(fbc).

this RFC: https://wiki.php.net/rfc/closure_self_reference

Or this, although this looks pretty stale.

[iluuu1994]

Actually, this can be solved rather simply with a Closure::getCurrent() function. Maybe that would be simple alternative to a by-ref bound variable. I'll create a PR shortly and see what internals think.