Anything involving Eclipse is always epic. First, you have to get your head around what distribution of it to use, as confusing as one's first introduction to Linux distributions (there are different kinds of Linux?).

Next, you have to grok the fact that the Zend Debugger must be installed on your server. In this case, MAMP.

Then, you have to make Eclipse listen to the debugging information being outputted, on the debug port.

Finally, you have to figure out how to use a debugger effectively (not in scope, but careful, debugging will blow your mind).

Every 6 months or so I take a stab at setting up line-level, breakpoint style debugging for PHP. In the past I've been able to get the debugger installed, but the lack of a decent interface to use in setting breakpoints and watches has limited the value of a debugger (one thing that I have found helpful is XDebug's profiling feature that lists all function calls in a nested format along with performance timing). The recent announcement of a new XDebug client for OS X got me back on that track, and while I wasn't able to get MacGDBP working as I wanted, it did lead me to re-evaluate the newest Eclipse offering for PHP coders: PDT. PDT has come a long way, and the combination of a robust IDE, nimble 'jumpt to' shortcuts and killer debugger integration are more than I can pass up. Here's how I got everything working on a Mac OS X 10.5 box.

Much of what follows was made possible by and incorporates instructions from these very good tutorials: