struct_module.rb

struct_module.rb

# coding: utf-8
require "struct_module/version"

module StructModule
  class << self
    def generate_module(attrs)
      Module.new{|mod|
        @_members = attrs

        def self.included(base)
          # XXX 手抜き感ある
          base.class_eval <<-END
            attr_accessor #{StructModule.args_to_symbollist(@_members)}
            def initialize(#{StructModule.args_to_argstring(@_members)})
              #{StructModule.args_to_assignstring(@_members)}
            end
            def self.members
              [#{StructModule.args_to_symbollist(@_members)}]
            end
          END
        end
      }
    end

    def args_to_symbollist(args)
      args.map{|name| ":#{name}"}.join(', ')
    end

    def args_to_argstring(args)
      args.map{|name| "#{name} = nil"}.join(', ')
    end

    def args_to_assignstring(args)
      args.map{|name| "@#{name} = #{name}"}.join('; ')
    end
  end
end

def StructModule(*args)
  StructModule.generate_module(args)
end

__END__

# sample
class C
  include StruceModule(:foo, :bar)
end

c = C.new        #=> #<C:0x007ff22a3acf68 @bar=nil, @foo=nil>
c.foo            #=> nil
c.foo = 1        #=> 1
c.foo            #=> 1
c2 = C.new(2, 3) #=> #<C:0x007ff22a4044c0 @bar=3, @foo=2>
c2.bar = 4       #=> 4
C.members        #=> [:foo, :bar]