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Date: Mon, 19 Mar 2007 14:30:49 -0400
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To: Stanislav Malyshev <stas@zend.com>
CC: Wez Furlong <wez@omniti.com>,  internals@lists.php.net
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Subject: Re: [PHP-DEV] PATCH: anonymous functions in PHP
From: sean@caedmon.net (Sean Coates)

> Well, making it work makes this thing closure. Otherwise it's just a
> nice way to save a couple of keystrokes :) Not to diminish your work,
> but there's a danger people would think it is closure because it looks
> like one (i.e., in other languages closures look exactly this way, e.g.
> Javascript).

I think this is the key to this whole discussion.

I doubt PHP will ever be able to fully support JavaScript- and
Lisp-style closures.

To take Stas' example to another level:

function foo()
{
  $bar = function () { echo "bar"; }
  return $bar;
}
$bar = foo();
$bar(); // does this work?

According to our current current syntax:
function foo()
{
  $bar = create_function('', 'echo "bar";');
  return $bar;
}
$bar = foo();
$bar(); // this does work

I don't know Lisp very well at all, but in JavaScript, functions are
general containers, and this sort of thing works fine, albeit VERY
differently. PHP's scoping rules are already completely different from
JavaScript's (there's no way to access the parent scope unless it
happens to be the global scope).

I strongly prefer Wez's syntax for anonymous function declaration. It
would help on many levels, from readability to syntax-highlighting, to
optimization (maybe...).

On optimization, the question becomes "how does Wez's proposal tokenize?"

--------Old:
T_OPEN_TAG                    : <?php
T_VARIABLE                    : $bar
T_WHITESPACE                  :
                                =
T_WHITESPACE                  :
T_STRING                      : create_function
                                (
T_CONSTANT_ENCAPSED_STRING    : ''
                                ,
T_WHITESPACE                  :
T_CONSTANT_ENCAPSED_STRING    : 'echo "bar";'
                                )
                                ;
--------New:
T_OPEN_TAG                    : <?php
T_VARIABLE                    : $bar
T_WHITESPACE                  :
                                =
T_WHITESPACE                  :
T_FUNCTION                    : function
                                (
                                )
T_WHITESPACE                  :
                                {
T_WHITESPACE                  :
T_ECHO                        : echo
T_WHITESPACE                  :
T_CONSTANT_ENCAPSED_STRING    : "bar"
                                ;
T_WHITESPACE                  :
                                }
                                ;

If the answer is "New", then this could be compiled at.. well,
compile-time, not at execute time. That could be even more interesting.

(sorry for the long post.. most of it's code (-; )

S