Is it possible to add asynchronous loop call function ?

On Fri, Nov 24, 2023 at 11:27 AM Michał Marcin Brzuchalski
michal.brzuchalski@gmail.com wrote:

Hi Robert,

pt., 24 lis 2023 o 10:24 Robert Landers landers.robert@gmail.com napisał(a):

...
You can also emulate this with:

class Defer {
private function __construct(private \Closure $callback) {}
public function __destruct() { $this->callback(); }
public static function _(\Closure $callback) { return new self($callback); }
}

and use it like:

function writeSomeStuff() {
// open files
$deferred = Defer::_($closeFiles(...));
// do stuff
}

So long as a reference exists to $deferred variable, the deferred
method won't be run. If the variable is local to the method/function
being run it, the deconstructor will be called after the function
returns.

It isn't the most beautiful thing in the world, and easy to forget to
store the result of Defer, but it is handy sometimes.

This is interesting which makes me thinking if forget to store it could be prevented.
I think requiring a ref could help with that:

class Defer {
private function __construct(private \Closure $callback) {}
public function __destruct() { ($this->callback)(); }
public static function _(\Closure $callback, &$var) { $var = new self($callback); }
}

$deferred = Defer::_($closeFiles(...), $foo);

Without $foo there'd be an ArgumentCountError.

Cheers,
Michał Marcin Brzuchalski

Hey Michael,

Thinking about it some more, I think we can go even further than that
and actually implement defer (enjoying the code golf)!

function defer(mixed &$anchor, \Closure $deferred): void {
if(is_resource($anchor)) {
$anchor = new class($anchor) {
public function __construct(public readonly mixed $resource) {}
};
}
static $mapping = new WeakMap();
$mapping[$anchor] = new class($deferred) {
public function __construct(private \Closure $deferred) {}
public function __destruct() { ($this->deferred)(); }
};
}

function writeFiles() {
$handle = fopen("/tmp/scratch.php", "wb");
// todo: write data
defer($handle, static function() use ($handle) {
echo "\ndeferred\n";
fclose($handle);
});
echo "\nafter defer()\n";
}

writeFiles();
echo "\nafter writeFiles()\n";

or something like that.