18.2 Edebug

Edebug is a source-level debugger for Emacs Lisp programs, with which you can:

• Step through evaluation, stopping before and after each expression.
• Set conditional or unconditional breakpoints.
• Stop when a specified condition is true (the global break event).
• Trace slow or fast, stopping briefly at each stop point, or at each breakpoint.
• Display expression results and evaluate expressions as if outside of Edebug.
• Automatically re-evaluate a list of expressions and display their results each time Edebug updates the display.
• Output trace information on function calls and returns.
• Stop when an error occurs.
• Display a backtrace, omitting Edebug's own frames.
• Specify argument evaluation for macros and defining forms.
• Obtain rudimentary coverage testing and frequency counts.

The first three sections below should tell you enough about Edebug to start using it.

• Using Edebug: Introduction to use of Edebug.
• Instrumenting: You must instrument your code in order to debug it with Edebug.
• Modes: Execution modes, stopping more or less often.
• Jumping: Commands to jump to a specified place.
• Misc: Miscellaneous commands.
• Breaks: Setting breakpoints to make the program stop.
• Trapping Errors: Trapping errors with Edebug.
• Views: Views inside and outside of Edebug.
• Eval: Evaluating expressions within Edebug.
• Eval List: Expressions whose values are displayed each time you enter Edebug.
• Printing in Edebug: Customization of printing.
• Trace Buffer: How to produce trace output in a buffer.
• Coverage Testing: How to test evaluation coverage.
• The Outside Context: Data that Edebug saves and restores.
• Edebug and Macros: Specifying how to handle macro calls.
• Options: Option variables for customizing Edebug.