ruby – 如何在mixin方法中访问实例变量？

一个有用的策略是Mixin总是通过访问器访问变量.所以,而不是：

#!/usr/bin/ruby1.8

module Mixin

  def do_something
    p @text
  end

end

class Foo

  include Mixin

  def initialize
    @text = 'foo'
  end

end

Foo.new.do_something     # => "foo"

mixin访问由包含类定义的“文本”访问器：

module Mixin

  def do_something
    p text
  end

end

class Foo

  attr_accessor :text

  include Mixin

  def initialize
    @text = 'foo'
  end

end

Foo.new.do_something     # => "foo"

如果您需要在本课中包含Mixin,该怎么办？

class Foo

def initialize
  @text = "Text that has nothing to do with the mixin"
end

end

在包含类使用相同的名称时,在混合中使用通用和通用数据名可能会导致冲突.在这种情况下,让mixin以较不常见的名称查找数据：

module Mixin

  def do_something
    p mixin_text
  end

end

并让include类定义适当的访问器：

class Foo

  include Mixin

  def initialize
    @text = 'text that has nothing to do with the mixin'
    @something = 'text for the mixin'
  end

  def mixin_text
    @something
  end

end

Foo.new.do_something     # => "text for the mixin"

以这种方式,访问器在混合数据和包含类的数据之间作为一种“阻抗匹配器”或“翻译器”.