摘要：
第三天做改进本节生成的XML程序，增加空格以显示缩进结构。Builder := Object cloneBuilder depth ::= 0Builder forward := method( #depth ::= 0 prefix := (" " repeated (self depth)) writeln(prefix, "<", call message name, ">") #depth = (depth +1) self setDepth(self depth + 1) call message argumen 阅读全文
