Fun with ticks.

gistfile1.txt

<?php

declare(ticks=1);

// A function called on each tick event
function tick_handler()
{
    echo "tick_handler() called\n";
    $trace = debug_backtrace();
    if (count($trace) <= 1) {
         return;
    }
    print_r($trace);
    $frame = $trace[1];
    unset($trace);
    $function = $frame['function'];
    echo __FUNCTION__ . ' :: ' . $function . PHP_EOL;
}

register_tick_function('tick_handler');

$a = 1;

if ($a > 0) {
    $a += 2;
    print($a);
}
do_something();
function do_something() { do_more(); }
function do_more() { }