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rubydebuggingirbmonkeypatching

Poking around/debugging in IRB. Monkey-patch a method, then "undo" that change, without quitting IRB?

I find IRB extremely useful as a tool for trial and error style debugging, where I don't really know where a problem is coming from, but can take advantage of the REPL nature of IRB to quickly iterate through a list of potential ways to reproduce an issue and distill it down.

Occasionally I decide to re-open a class belonging to a loaded gem and add some debug output to a method, or override the method entirely. Once that is done, is there an easy to way "un-monkey patch" the class, without quitting IRB and restarting it (my current approach)?

Solution

  • If you're redefining a method, you could create and alias for the old method and then define your new one. When you're done, you could redefine the method yet again and call the method alias.

    Step one:

    alias :old_method :method

def method
  # fancy new stuff
end

    When you're done:

    def method
  old_method
end