is eval() bad?

[Anon]

i was told that eval() function reduces performance because php works by having a parser which parses the code in to some kind of parse-tree, then an interpreter which goes through the parse tree line-by-line executing the commands. so when php hits an eval() function it will be operating in interpreter mode, but will then be forced to jump back in to parse mode to analyse the string, before jumping back again in to interpreter mode to execute it. if this is the case what can i do instead of eval my code which is stored in a database?

[Anon]

I used eval() some times and it worked ok. Make a test... calculate the number of seconds (or microseconds) it will take to the computer to eval your code. (of course, in the delay will be counted the execution of your code, not just only the time it took to eval to "eval"...)

For seconds :

$start = ereg_replace("^. ", "", microtime());
eval($my_code);
$end = ereg_replace("^. ", "", microtime());
$delay = $end - $start;
echo $delay;

Microseconds :

$time = gettimeofday();
$start_microsc = $time["usec"];
eval($my_code);
$time = gettimeofday();
$end_microsc = $time["usec"];
$delay = $end_microsc - $start_microsc.
echo $delay;

Hope it helped.