This gem allows you to guard methods that have side effects with a callback that fires before the method is invoked. If the callback returns a "falsey" value, the method is halted and will not be called, and the result will be nil instead. if the method does not have side effects or you depend on its return value, you should NOT use this on that method! This will break the hell out of design by contract. Currently does not work with methods that accept blocks so be aware of that. Fixes, improvements, pull requests, and general "why on earth did you do this" notes are encouraged.

Currently tested/developed on 1.8.7. If you're no longer working with a hammer and chisel (using 1.9.2) then this may or may not work for you, and there are definitely better ways to do this. Future development will include 1.9.2 support, support for methods that take blocks, allowing the guard_method method to take a block or lambda instead of just a symbol, and more.

NOTES/HOWTOS:

INSTALL:

gem install method_cop

USE:

require 'method_cop'

class Citizen
  extend MethodCop
  guard_method :something_illegal, :with => :allow_action?

  def allow_action?
    false
  end

  def something_illegal
    "Murder"
  end
end

Citizen.new.something_illegal
=> nil

BUGS:

The ones I know of offhand are:

-Doesn't play nice with methods that take blocks -Ignores methods that were already defined when the guard_method call happened