MixInの練習

mixin.rb

[1] pry(main)> module MixIn
[1] pry(main)*   def hello
[1] pry(main)*     puts "hello from MixIn"
[1] pry(main)*   end
[1] pry(main)* end
=> :hello
[2] pry(main)> class A
[2] pry(main)*   include MixIn
[2] pry(main)* end
=> A
[3] pry(main)> a = A.new
=> #<A:0x007faffa4bcda8>
[4] pry(main)> a.hello
hello from MixIn
=> nil
[5] pry(main)> class B
[5] pry(main)*   include MixIn
[5] pry(main)*   def hello
[5] pry(main)*     puts "hello from class B"
[5] pry(main)*   end
[5] pry(main)* end
=> :hello
[6] pry(main)> b = B.new
=> #<B:0x007faff99ffed8>
[7] pry(main)> b.hello
hello from class B
=> nil

継承ツリーの一番下からたどるのでMixIn先にmethodがあってもMixIn元が優先される