When to use `method_missing`
metaprogramming, ruby
Solution
It's entirely safe to use provided you use it in expected ways and don't get carried away. Not everything you can do is worth doing, after all.
The advantage of `method_missing` is you can respond to all kinds of things in unique ways.
The disadvantage is you don't advertise your capabilities. Other objects that expect you to `respond_to?` something will not get confirmation and might treat your custom object in ways you don't intend.
For building Domain Specific Languages and providing very loose glue between components, this sort of thing is invaluable.
A great example of where this is a good fit is the Ruby OpenStruct class.
Problem
In the code below, method `roar` is not defined in class `Lion`, but still can be called using `method_missing`. ``` class Lion def method_missing(name, *args) puts "Lion will #{name}: #{args[0]}" end end lion = Lion.new lion.roar("ROAR!!!") # => Lion will roar: ROAR!!! ``` In which situations and how should I use this `method_missing`? And is it safe to use?