From: ts <decoux@...>
Date: 2002-01-13T23:42:11+09:00
Subject: Re: Conflicting method names with modules

>>>>> "J" == Jonathan Lim <trayde@dial.pipex.com> writes:

J> class ScaleDemo

 at this step you have ScaleDemo < Object

J>         include MajorScales

 ruby will insert the module just before ScaleDemo, this give

           ScaleDemo < MajorScales < Object

J>         include PentatonicScales

 ruby will insert the module just before ScaleDemo, this give

           ScaleDemo < PentatonicScales < MajorScales < Object

J>         def initialize

J>                 puts majorNum # Should be 7
J>                 puts pentaNum # Should be 5

 These 2 methods are called in the context of the new object (self), this
 mean that ruby will set the instance variable for this object. This is why
 it return 7 in the 2 cases (pentaNum don't change the instance variable if
 it's always defined)

J>                 testmethod

 Now ruby search the method #testmethod : it search in ScaleDemo, then in
 PentatonicScales and find it here.

J>         end
J> end

 If you define a module function, ruby will create
   1) a private method
   2) a public singleton method

 This mean than you can write

pigeon% cat b.rb
#!/usr/bin/ruby
module MajorScales
   def majorNum
      7
   end
   def testmethod
      puts "MajorScales test method"
   end
   module_function :testmethod
end

module PentatonicScales
   def pentaNum
      5
   end
   def testmethod
      puts "Pent test method"
   end
   module_function :testmethod
end

class ScaleDemo
   include MajorScales
   include PentatonicScales

   def initialize
      puts majorNum # Should be 7
      puts pentaNum # Should be 5
      
      testmethod
      PentatonicScales::testmethod
      MajorScales::testmethod
   end
end

ScaleDemo.new
pigeon% 

pigeon% b.rb
7
5
Pent test method
Pent test method
MajorScales test method
pigeon% 


Guy Decoux