On Fri, Jul 16, 2010 at 10:21 PM, David Krings <ram...@gmx.net> wrote:
> Uhm, for the ones like me who have no clue what this means, any pointers
> available that explain closures?
You can read about closures until you are blue in the face. The first
thing you have to grock is first-class functions. Which basically
means a variable can be a function. We normally think of variables as
"data", but there is no reason you can't store a procedure in a
variable. Once you understand that functions are just another type of
variable, then you can write functions that create other functions.
e.g. you can return a function from a function. The following code
illustrates the concept, and is valid php 5.3
<?php
$add1 = function($val) {
echo $val+1,"\n";
};
$add1(5); // prints 6
function makeAdder($num) {
return function($how_many) {
echo $how_many + $num, "\n";
};
}
$add6 = makeAdder(6);
$add6(3); // prints 3, but why?
function makeAdderClosure($num) {
return function($how_many) use ($num) {
echo $how_many + $num, "\n";
};
}
$add5 = makeAdderClosure(5);
$add5(3); // prints 8;
$add4= makeAdderClosure(4);
$add4(4); // prints 8;
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