Simple XML Output with method_missing
#代码实例：pagetitle = "Test Page for XML.generate"XML.generate(STDOUT) do html do head do title { pagetitle } comment "This is a test" end body do h1(:style => "font-family:sans-serif") { pagetitle } ul :type=>"square" do li { Time.now } li { RUBY_VERSION } end endendend 生成结果：<html><head><title>Test Page for XML.generate</title><!-- This is a test --></head><body><h1 style='font-family:sans-serif'>Test Page for XML.generate</h1><ul type='square'><li>2007-08-19 16:19:58 -0700</li><li>1.9.0</li></ul></body></html>代码实现：
class XML# Create an instance of this class, specifying a stream or object to# hold the output. This can be any object that responds to <<(String).def initialize(out) @out = out# Remember where to send our outputend# Output the specified object as CDATA, return nil.def content(text) @out << text.to_s nilend# Output the specified object as a comment, return nil.def comment(text) @out << "<!-- #{text} -->" nilend# Output a tag with the specified name and attributes.# If there is a block invoke it to output or return content.# Return nil.def tag(tagname, attributes={}) # Output the tag name @out << "<#{tagname}" # Output the attributes attributes.each {|attr,value| @out << " #{attr}='#{value}'" } if block_given? # This block has content @out << '>' # End the opening tag content = yield # Invoke the block to output or return content if content # If any content returned @out << content.to_s# Output it as a string end @out << "</#{tagname}>" # Close the tag else # Otherwise, this is an empty tag, so just close it. @out << '/>' end nil # Tags output themselves, so they don't return any contentend# The code below is what changes this from an ordinary class into a DSL.# First: any unknown method is treated as the name of a tag.alias method_missing tag# Second: run a block in a new instance of the class.def self.generate(out, &block) XML.new(out).instance_eval(&block)endend
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