Info Catalog eintr: edebug eintr: Debugging

eintr: Debugging Exercises

 
 17.5 Debugging Exercises
 ========================
 
    • Install the ‘count-words-example’ function and then cause it to
      enter the built-in debugger when you call it.  Run the command on a
      region containing two words.  You will need to press ‘d’ a
      remarkable number of times.  On your system, is a hook called after
      the command finishes?  (For information on hooks, see Command
      Loop Overview (elisp)Command Overview.)
 
    • Copy ‘count-words-example’ into the ‘*scratch*’ buffer, instrument
      the function for Edebug, and walk through its execution.  The
      function does not need to have a bug, although you can introduce
      one if you wish.  If the function lacks a bug, the walk-through
      completes without problems.
 
    • While running Edebug, type ‘?’ to see a list of all the Edebug
      commands.  (The ‘global-edebug-prefix’ is usually ‘C-x X’, i.e.,
      ‘<CTRL>-x’ followed by an upper case ‘X’; use this prefix for
      commands made outside of the Edebug debugging buffer.)
 
    • In the Edebug debugging buffer, use the ‘p’ (‘edebug-bounce-point’)
      command to see where in the region the ‘count-words-example’ is
      working.
 
    • Move point to some spot further down the function and then type the
      ‘h’ (‘edebug-goto-here’) command to jump to that location.
 
    • Use the ‘t’ (‘edebug-trace-mode’) command to cause Edebug to walk
      through the function on its own; use an upper case ‘T’ for
      ‘edebug-Trace-fast-mode’.
 
    • Set a breakpoint, then run Edebug in Trace mode until it reaches
      the stopping point.
 

Info Catalog eintr: edebug eintr: Debugging