17 Debugging

GNU Emacs has two debuggers, debug and edebug. The first is built into the internals of Emacs and is always with you; the second requires that you instrument a function before you can use it.

Both debuggers are described extensively in Debugging Lisp Programs. In this chapter, I will walk through a short example of each.

• debug: How to use the built-in debugger.
• debug-on-entry: Start debugging when you call a function.
• debug-on-quit: Start debugging when you quit with C-g.
• edebug: How to use Edebug, a source level debugger.
• Debugging Exercises