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/