Assign to a variable in the condition of a while loop - scala

Question

I Java I can write this:

Matcher m;
while ((m = pattern.matcher(string)).matches()) {...}

How would I do this in Scala? This doesn't work :

var m: Matcher = null
while ((m = pattern.matcher(s)).matches()) {}

serejja · Accepted Answer · 2014-03-26 13:13:51Z

9

Assignments return Unit in Scala, but it's ok to use code blocks like this:

while ({
  val m = pattern.matcher(s)
  m.matches
}) { ... }

answered Mar 26, 2014 at 13:13

serejja

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3 Comments

Sohaib Over a year ago

If I want to use the val m in the body of the loop?

serejja Over a year ago

@Sohaib As I know there's no clean way to do it without using var. But if you're ok with that you may just use this: var m: Matcher = null; while ({ m = pattern.matcher(s); m.matches}) { ... }

worldterminator Over a year ago

yeah, it looks ugly, I always use breakable loop which throws exception. Did they fix it in dotty?

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