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Debugging

Basic debugging is very similar in CodeWarrior and Xcode, though Xcode uses the open source GDB debugger and provides some additional features, such as Fix and Continue (live patching), to make debugging more efficient. Xcode supplies a graphical interface to GDB, but you can also use the command line interface (in place of or in parallel to the UI) to get full access to any GDB feature not supported in the user interface. Figure 1-7 shows the debugger window stopped in a simple Carbon application.

For GDB documentation, see Debugging with GDB.Note that some debugging features are currently unavailable in Xcode: for example, you cannot set event points in the UI.

In CodeWarrior, “event points” are the general name for a set of actions that the CodeWarrior IDE debugger can perform at a breakpoint (such as perform a test, log a message, play a sound, speak a phrase, or execute a script). A “watch point” is a range of memory that you are watching while debugging to note changes; the debugger stops execution when it notices that a certain range of memory has been changed.

Beginning with Xcode 2.1, Xcode includes support for both breakpoint actions and watchpoints. Similar to event points, breakpoint actions let you perform an action at a breakpoint. Xcode includes breakpoint actions that let you execute a script, print a message to the console, send a command to the debugger, and more.

While CodeWarrior supplies nonstandard flags to perform diagnostics on use of the standard template library (STL), Xcode does not include a debug version of the STL. However, Xcode does support breaking on C++ try, catch and throw constructs, and allows stepping through template instantiation.

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