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Subject: Re: [PHP-DEV] [RFC] Closure::call and Function Referencing as Closures
From: ralph@ralphschindler.com (Ralph Schindler)

Andrea + Marco

> Is the advantage of `Closure#call()` only performance? Because I don't see
> other advantages otherwise, and I don't think the performance impact is
> relevant.

I like the proposal, but with some modifications.  I am unsure if there 
is another RFC out there on function de-referencing, but at current the 
following is not possible:

   $x = function() { return function () { echo 'hi'; }; };
   $x()();

Nor is de-referencing of a closure assigned to an object property:

   class Foo { public $bar; }
   $f = new Foo;
   $f->bar = function () { echo 'hi'; };
   $f->bar();

While those are less important on their own, the use case that this does 
address is the ability to inline call a closure assigned to an 
object(/or class) property and fluently without call_user_func:

   class Foo { public $bar; }
   $f = new Foo;
   $f->bar = function () {
     echo 'hi'; return function () {
       echo ' world';
     };
   };
   call_user_func(call_user_func($f->bar));

"->call()" would facilitate the following syntax, which I'd argue has 
greater semantic meaning than the call_user_func() variant:

   $f->bar->call()->call();

Additionally, the above assumes the following modification to the RFC: 
the additional of bindCall(), or something similarly named.  The purpose 
here is to be able to call(/* args */) an existing closure with the 
current bound context (as a result from a previous bindTo) and 
bindCall($context, /* args */); to support the bind-and-call workflow.

The reason for call() to operate on existing bound context would be this 
workflow:

   class Foo {
     public $bar;
     public function registerBar(\Closure $c) {
       // bind to specific scope as per Foo's specifications
       $this->bar = $c->bindTo(...);
     }
   }
   $f = new Foo;
   $f->registerBar(function () {
     echo 'hi'; return function () {
       echo ' world';
     };
   });

   $f->bar->call();

   // if you must change context:

   $f->bar->bindCall($otherContext);


Thanks,
Ralph Schindler