OREILLY版《Programming Scala》学习笔记——Trait//if you don’t use extends for the first trait, e.g., y
O'REILLY版《Programming Scala》学习笔记——Trait
//if you don’t use extends for the first trait, e.g., you write the following:// error:class observablebutton(name: string) with button(name) with subject {...}
