Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.1k views
in Technique[技术] by (71.8m points)

scala - What is return type of `if` statement

From Programming Scala book I read that in following code configFilePath constant will be type of Unit:

scala> val configFilePath = if (configFile.exists()) {
| configFile.getAbsolutePath()
| }
configFilePath: Unit = ()

But when I execute this code in REPL I get result of type Any. Why?

The book examples use Scala 2.8, and I use Scala 2.10.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

if (cond) { expr } returns common base type of Unit and type of expr, just like if (cond) { expr } else { () }.

It is AnyVal for Int, Char and so on, Unit for Unit and Any for AnyRef:

scala> if ( false ) 1
res0: AnyVal = ()

scala> val r = if ( false ) { () }
r: Unit = ()

scala> if ( false ) ""
res1: Any = ()

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

1.4m articles

1.4m replys

5 comments

57.0k users

...