什么区别.new来自.new（true）？ ＆＃34;缩进＆＃34; Test-First-Ruby中的XML文档

Question

我正在解决这些问题，并且有点坚持如何完成这个问题。这是RSPEC，特别麻烦我的是最后一个＆＃34;它缩进＆＃34;测试：

# # Topics
#
# * method_missing
# * blocks
# * strings
# * hashes

require "13_xml_document"

describe XmlDocument do
  before do
    @xml = XmlDocument.new
  end

  it "renders an empty tag" do
    @xml.hello.should == "<hello/>"
  end

  it "renders a tag with attributes" do
    @xml.hello(:name => 'dolly').should == "<hello name='dolly'/>"
  end

  it "renders a randomly named tag" do
    tag_name = (1..8).map{|i| ('a'..'z').to_a[rand(26)]}.join
    @xml.send(tag_name).should == "<#{tag_name}/>"
  end

  it "renders block with text inside" do
    @xml.hello do
      "dolly"
    end.should == "<hello>dolly</hello>"
  end

  it "nests one level" do
    @xml.hello do
      @xml.goodbye
    end.should == "<hello><goodbye/></hello>"
  end

  it "nests several levels" do
    xml = XmlDocument.new
    xml.hello do
      xml.goodbye do
        xml.come_back do
          xml.ok_fine(:be => "that_way")
        end
      end
    end.should == "<hello><goodbye><come_back><ok_fine be='that_way'/></come_back></goodbye></hello>"
  end

  it "indents" do
    @xml = XmlDocument.new(true)
    @xml.hello do
      @xml.goodbye do
        @xml.come_back do
          @xml.ok_fine(:be => "that_way")
        end
      end
    end.should ==
    "<hello>\n" +
    "  <goodbye>\n" +
    "    <come_back>\n" +
    "      <ok_fine be='that_way'/>\n" +
    "    </come_back>\n" +
    "  </goodbye>\n" +
    "</hello>\n"
  end
end

我觉得我理解这个问题，解决方案就像是

"<#{method}>\n" + "  #{yield}" + "</#{method}>\n"

给出我的代码：

    class XmlDocument
#use method missing so that arbitrary methods 
#can be called and converted to XML

    def method_missing(method, hash=nil, &block)
         if (hash == nil && block == nil)
             "<#{method}/>"
         elsif hash.is_a?(Hash)
             #renders tag with attributes (from hash)

             my_key = nil
             my_val = nil
             hash.each do |key, value|
                 my_key = key
                 my_val = value
             end
             "<#{method} #{my_key}='#{my_val}'/>"
         else
             #passes whatever to between tags including nested methods.

             "<#{method}>#{yield}</#{method}>"
         end
    end

end

我的问题是我不知道如何区分＆＃34;它嵌套了几个级别＆＃34;测试来自＆＃34;它缩进＆＃34;测试所以我可以把它放到我的＆＃34; if＆＃34;声明。唯一可以区分它们的是＆＃34;它缩进＆＃34;测试已经

@xml = XmlDocument.new(true)

＆＃34; true＆＃34;是什么意思？作为#new的论据？它与我的问题有关吗？

Answer 1

初始化时，可以将参数传递给对象。在这种情况下，您希望该值默认为false。这样，缩进代码仅在调用XmlDocument.new(true)时运行。

class XmlDocument
    def initialize(indent = false)
        @indent = indent
    end

    def method_missing(method, args=nil, &block)
        if @indent == true
            #run with indents
        else
            #run without indents
        end
    end
end