I, too, was wondering whether is_callable or function exists is faster when checking class methods. So, I setup the following test:
<?php
function doTimes($start, $end)
{
$start_time = explode (" ", $start);
$start_time = $start_time[1] + $start_time[0];
$end_time = explode (" ", $end);
$end_time = $end_time[1] + $end_time[0];
$time = $end_time - $start_time;
return $time;
}
class test
{
function test()
{
return true;
}
}
$callableIsTrue = false;
$startIsCallable = microtime();
for($i = 0; $i < 10000; $i++)
{
if(is_callable(array('test', 'test'))) { $callableIsTrue = true; }
}
$endIsCallable = microtime();
$existsIsTrue = false;
$startExists = microtime();
for($i = 0; $i < 10000; $i++)
{
if(function_exists('test::test')) { $existsIsTrue = true; }
}
$endExists = microtime();
$timeIsCallable = doTimes($startIsCallable, $endIsCallable);
$timeExists = doTimes($startExists, $endExists);
echo "<b>is_callable = ".($callableIsTrue ? "TRUE" : "FALSE")."</b>, \n";
echo "<b>function_exists = ".($existsIsTrue ? "TRUE" : "FALSE")."</b><br>\n";
echo "<br>Did 10000 is_callables in ".$timeIsCallable." seconds";
echo "<br>Did 10000 function_exists in ".$timeExists." seconds";
?>
This gives the output :
is_callable = TRUE, function_exists = FALSE
Did 10000 is_callables in 0.0640790462494 seconds
Did 10000 function_exists in 0.0304429531097 seconds
So the fact that function_exists is twice as fast is slightly over shadowed by the fact that it doesn't work on class methods, at least not as far as I can tell.
