Creating new Ruby string helper without argument params -

I had a really hard time to tell this question, but in a nutshell, I want to do this :

Model = MyModel.new model.title = "foo bar" model.title.to_id # = & gt; "Foo_bar"

I have an ActiveRecord class for MyModel

  code  MyModel & lt; ActiveRecord :: Base def to_id (str) str.downcase.gsub ("", "_") Ending  

But, of course, it is looking for the to_id method on the string, And I do not want to override the string, because I do not need this behavior on every string. The wire associated with MyMold can make it simple and do something like this:

  model.to_id (model.title)  

but it Not very Ruby.

I know I have seen examples of this type of method first, I can not track them down.

Anyone?

You can use a specific object instance with a method, module.

  module ToId def to_id self.downcase.gsub "", "_" and end class MyClass def title = (value) value.extend ToId @title = value end def title @title end end M = MyClass.new m.title = "foo bar" puts m.title # => foo bar, m.title.to_id # => foo_bar  

Since value .title = Method, when we increase the string string with the ToId module, the methods of "self" modules have a string, therefore, we have direct access to the string, which was passed in the .title = method, And we can manipulate it directly Are there.

All this is done without modifying the string class directly. We are only expanding the specific example that represents the title.