如下：
D:\code\api_sdk_proj\meta-idl>scala
Welcome to Scala version 2.10.2 (Java HotSpot(TM) Client VM, Java 1.6.0_25).
Type in expressions to have them evaluated.
Type :help for more information.
scala> case class A(s:String)
defined class A
scala> val a=A("argan")
a: A = A(argan)
scala> a.s
res0: String = argan
scala> println(f"a.s=$a.s")
a.s=A(argan).s
scala> a
res2: A = A(argan)
scala> println(f"a.s=${a.s}")
a.s=argan
scala>
