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Subject: Re: [PHP-DEV] PATCH: anonymous functions in PHP
From: stas@zend.com (Stanislav Malyshev)

> This gets incredibly complex not only to figure out what to do in the
> PHP source, but for scripters to figure out what the heck it does...

Welcome to the world of closures :) But in most cases people use it to 
do pretty basic stuff (unless they are CS majors with too much time on 
their hands ;) - like creating "dynamic anonymous functions" - basically 
resulting in the same as what create_function does, and some currying - 
which, for those who doesn't know it, is technique of partially 
instantiating a multi-argument function - i.e. making something like:

$addtwo = function ($a) { return $a+2; }
$six = $addtwo(4);

or more frequently something like this:

$var = "foo";
$compare_to_var = function($s) { return (str_compare($var, $s)<0); }
$strings_less_than_var = array_filter($array, $compare_to_var);

which is really powerful technique for dynamic language, though can 
easily lead one to lose all track of what is happening if overused. For 
more confusion see http://en.wikipedia.org/wiki/Currying :)

> If it's making YOUR head spin, what will it do to the poor unwashed
> masses?...

Unwashed masses better not do it :) Actually many "washed" masses have 
hard time to understand these things too.

> I suspect that you could get away with JUST using global and/or static
> as they exist now, not introduce yet another scoping keyword, and
> anything that *NEEDS* to be done with an anonymous function can be
> done.

I guess this depends on definition of "NEEDS".

> You have to have a pretty esoteric function to need that kind of scope
> control, no?

Depends on your background. Some people consider LISP intuitive language 
:) And if you work with Javascript, you probably would be doing it daily 
- most AJAX toolkits rely on heavy usage of anonymous functions. Not 
sure it needs to be in PHP though. It might be cool thing, but it's 
definitely becomes very confusing very fast.
-- 
Stanislav Malyshev, Zend Products Engineer
stas@zend.com  http://www.zend.com/