With()

Negroni 还有一个便利的函数叫 With. With 函数可以把一个或多个 Handler 实例和接收者处理器集合组合成新的处理器集合，并返回新的 Negroni 实例对象。

// middleware we want to reuse
common := negroni.New()
common.Use(MyMiddleware1)
common.Use(MyMiddleware2)
 
// `specific` is a new negroni with the handlers from `common` combined with the
// the handlers passed in
specific := common.With(
  SpecificMiddleware1,
  SpecificMiddleware2
)