chanson

Mac OS X is ahead of the curve on this one too: tracepoints - get rid of your printf-style debugging! (James Manning)

An excellent feature in Whidbey is basically breakpoints that don’t actually stop execution – they’re called tracepoints.

Xcode 2.1, which shipped at WWDC in June, added advanced breakpoint support. This includes the ability to have breakpoints only stop on certain conditions, continue execution immediately or after a delay upon being hit, and to perform a variety of other actions when they're hit. For example, you can output a message, have the speech synthesizer speak some text, or even show where exactly you are in a class model diagram when a breakpoint is hit.

Check it out!