import groovy.xml.MarkupBuilder

MarkupBuilder.metaClass.define {
  fromString = { str, var = [:] ->
    def code = "{-> ${str} }" // a closure
    def received = new GroovyShell([var: var] as Binding).evaluate(code)
    received.delegate = delegate // MarkupBuilderにデリゲート
    received()
  }
  fromFile = { file, var = [:] ->
    delegate.fromString(file.getText('UTF-8'), var)
  }
}


int size = 100
def writer = new File('groovy_htmlbuilder_test.html').newPrintWriter('UTF-8')
def html = new MarkupBuilder(writer)
html.doubleQuotes = true // 属性は ' じゃなくて " で。
html.fromFile(new File('markup.ghtml'), [size: size]) // 引数も渡せる！
writer.close()