Is it possible to make an alias for a module in Ruby?

Question

In Python, you can set an alias for a module with 'as':

import mymodule as mm

But I can't seem to find an equivalent for ruby. I know that you can include rather than require a module, but this risks namespace collisions. Is there any equivalent to Python module aliases?

Inhibit

require and include are very different in ruby. They are not interchangeable with each other. – Lingerie

Answer 1

Modules in Ruby aren't really that special, so you can just assign them to another constant:

[4] (pry) main: 0> module TestModule
[4] (pry) main: 0*   def self.foo
[4] (pry) main: 0*     "test"
[4] (pry) main: 0*   end  
[4] (pry) main: 0* end  
=> nil
[5] (pry) main: 0> tm = TestModule
=> TestModule
[6] (pry) main: 0> tm.foo
=> "test"

Magee

@Sean, you can assign them to any variable. You should use local variables because they won't pollute global scope. Also, you won't have to use the shift key all the time. – Root

Answer 2

Michael's answer seems to solve your question... still, I read the question a bit differently and discovered something really nice that I thought worth sharing.

I understood your question as: "What do I do if I want to require two modules of the same name?", that is, how could I alias them if requiring both would result in a namespace clash? Because, as far as my understanding of Python's 'import ... as ...' goes, it also solves those kinds of problems. An example in Ruby:

#file a.rb
module A
  def self.greet
    puts 'A'
  end
end

#file b.rb
module A
  def self.greet
    puts 'other A'
  end
end

Now if I would do this in a third file:

require_relative 'a'
require_relative 'b'

A.greet # => other A

the first A would be completely overridden by the A in b.rb. Using Michael's trick also won't help:

require_relative 'a'
TMP_A = A
A.greet # => A
TMP_A.greet # => A
require_relative 'b'
TMP_A2 = A
A.greet # => other A
TMP_A2.greet # => other A
TMP_A.greet # => other A :(

Too bad. Then I thought, well, in Ruby there's the ubiquitous dup for making a clone of basically everything and without too much hope I just typed this and reran the program:

require_relative 'a'
TMP_A = A.dup
A.greet # => A
TMP_A.greet # => A
require_relative 'b'
TMP_A2 = A
A.greet # => other A
TMP_A2.greet # => other A
TMP_A.greet # => A :P

That totally made my day, hope you guys appreciate it as much as well. Now that I think about it, it makes sense - a module is an object like any other after all, so why shouldn't dup work?

Representational

Nice, "a module is an object like any other after all" was kinda the point of my answer too. :-) – Magee

@MichaelKohl Heh, true. I love it, there's so much to explore in Ruby :) – Representational

@Representational Nice, this is a highly worthy addition to this thread. Will keep it in mind for when I need two modules with the same name. – Inhibit

@Representational To help others find this answer, you might want to ask your interpretation of question and then post this as the answer to that. – Poltergeist