Debugging aids (after the style of: Error management)

Don't you like the side-benefits of this list, eg that someone comes up with a question that gets your thought processes running or suggests an idea you'd not otherwise come up with!? So further to the question: > How can I know the line and the file from where a function has called. I > already know __FILE__ and __LINE__, but I don't want to transmit them in > arguments. is there a debugging facility in PHP which displays a 'map' of which functions have called which? So for example, a script crashes at line_56 in file_fred.php, which is what we've all come to know and love; but I'd like to know that it got there by the mainline calling FnOpen(), which called FnInitialise(), which in turn called FnUncleTomCobbleighAndAll(), where some incompetent happily three layers down tried to share out the spoils by dividing by zero (or whatever)... Looking in the manual I started with: <<<<< Chapter 8. Constants Predefined constants A constant is a identifier (name) for a simple value. As the name suggests, that value cannot change during the execution of the script (the magic constants __FILE__ and __LINE__ are the only exception). A constant is case-sensitive by default. By convention constants are always uppercase. >>>>> but if these two are the only "magic constants" then I'm out of luck there. So I meandered through the PHPINFO and environment variables, but nothing stood up and popped me in the eye. Anyone know better/have a bright idea? =dn