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Subject: Re: [PHP-DEV] (non)growing memory while creating anoymous functions
 via eval()
From: petrich@tronic-media.com ("Hans-Juergen Petrich")

Hello

> Then again, your code still does not make sense to me ...
Fully understand :-)

Not want wasting your time with my specific situation... but there are  
situation where it make sense :-)


For example... in my situation, i have time intensive (mathematically)  
operations to do in pure php
and was searching a way to speed this operations up.

With PHP's eval() feature, creating php code at run time, this would be,  
in my situation, a possible way.



Very simplified, i have to deal with the following:

function calculate($ints)
{
   $result = 0;
   for ($i=0; $i<10000000; ++$i) {
    $result += $ints[0] + $ints[1] + $ints[2] + $ints[3] + $ints[4] +  
$ints[5];
   }
   return $result;
}
$ints = array(1,2,3,4,5,6);
$result = calculate($ints);



A faster way would be:

$ints = array(1,2,3,4,5,6);
eval('$calculate = function () {
   $result = 0;
   for ($i=0; $i<10000000; ++$i) {
    $result += '.$ints[0].' + '.$ints[1].' + '.$ints[2].' + '.$ints[3].' +  
'.$ints[4].' + '.$ints[5].';
   }
   return $result;
};');
$result = $calculate();



The function code it self is in reality more complex and variable in the  
function-body length, but the princip is the same.
The code-architecture, in my specific situation, requires also that the  
operation encapsulated in a function.
(And for security: It is ensured that $int is an 1-dim array filled only  
with integers)

$calculate() works very fine and, of course, much faster than the  
hardcoded calculate().
Each time $ints is changing i also have, of course, re-define/creater  
$calculate() via eval.

In such situations, for performance reasons, it would makes sense using  
eval() for re/creating ano-functions, doesn't it?

And as long as the function-body has a fixed length each time re/creating  
the ano-function via eval() it would also not let grow the memory endless.