From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-10-01T17:41:49+09:00
Subject: Re: How to prevent overwriting methods by accident?

On Thu, Sep 30, 2010 at 11:32 PM, Jeremy Bopp <jeremy@bopp.net> wrote:
> On 9/30/2010 2:53 PM, Alex Stahl wrote:
>> But is there a way to call the original method instead of just quitting
>> out?
>
> If you want to know if you can conditionally define the method and skip
> the exit, yes, you can.  Just leave out the else clause of the example.
>  That way, your method is called only if the original one didn't already
> exist.  I used this once to implement Enumerable#none? only under
> versions of Ruby where that method was not yet implemented.
>
> If you want to have a kind of functionality similar to that provided by
> the super keyword, you can do that too:
>
> class String
>  if method_defined?(:my_method) then
>    alias :my_method_orig :my_method
>  end
>
>  def my_method
>    # Maybe do some extra stuff here.
>    ...
>
>    # Call the original method if there is one.
>    if methods.include?("my_method_orig") then
>      my_method_orig
>    end
>
>    # Maybe do more extra stuff here.
>    ...
>  end
> end
>
> This will alias the original instance of my_method, if there is one, to
> my_method_orig.  Your new my_method definition can call the alias if it
> exists and skip it otherwise.  I suppose this would be good for
> instrumenting methods to add logging and the like, but I would take care
> with using this generally since it can make some unnecessarily
> complicated code.

Shouldn't we be using respond_to? instead of method_defined? or
methods.include?.
This way, if the method is handled dynamically through method_missing
you can check that too, and not "override" the behaviour.

Jesus.