Question

我有两个Ruby Module，其中一个逻辑上继承了＆＃39;从另一个：

module FileBacked
  attr_reader :file
  def file=( path )
    @file    = path
    @content = File.read(path,encoding:'utf-8') if File.exist(path)
  end
  def save!
    File.open(@file,'w:utf-8'){ |f| f << @content } if @file
  end
end

module XMLBacked
  attr_reader :doc
  def file=( path )
    super
    @doc = Nokogiri.XML(@content)
  end
  def save!
    @content = @doc.to_xml
    super
  end
end

因此，对super的调用将起作用，需要像以下一样使用它们：

class Foo
  include FileBacked # Always include this first
  include XMLBacked  # Always include this second
end

p Foo.ancestors
#=> [Foo, XMLBacked, FileBacked, Object, Kernel, BasicObject]

我希望能够写下：

class Bar
  include XMLBacked  # Also includes FileBacked
end

...但我无法弄清楚如何在搜索方法层次结构时导致FileBacked XMLBacked之后出现这种情况。

如果我入侵包含，则结果是错误的查找顺序：

module XMLBacked
  def self.included(klass)
    klass.instance_eval{ include FileBacked }
  end
end

class Jim
  include XMLBacked
end
p Jim.ancestors
#=> [Jim, FileBacked, XMLBacked, Object, Kernel, BasicObject]

如何在XMLBacked之后将FileBacked原因XMLBacked包含在查询链中？

Answer 1

答案存在于一个重复的问题中，尽管我最初没有看到它：

module XMLBacked
  include FileBacked
  # other XMLBacked methods here
end

这会导致FileBacked在XMLBacked之前注入XMLBacked，只要它包含{{1}}。

使模块预先包含另一个（模块继承）ruby

1 个答案: