Comments on: ‘in’ the groove

By: Steve

Steve — Tue, 19 Jan 2010 00:16:58 +0000

Sounds like “in” should sometimes be “is” … or perhaps “instanceof”?

Definitely come confusion around this point — but generally a very cool feature.

By: Dierk König

Dierk König — Thu, 14 Jan 2010 15:14:55 +0000

well, it only makes sense when considering the isCase() heritage.
“in” does _not_ denote a containment but a classification!

By: Peter

Peter — Thu, 14 Jan 2010 14:09:51 +0000

Thanks for the correction and clarification Dierk. I have to say, this is one instance where Groovy doesn’t do what I would expect it to. This works as you say:

def x = 1.0F
assert x in Float

but doesn’t make much sense to my eyes, whereas this doesn’t work:

def x = “st”
assert x in “string”

but I would expect it to. The BigDecimal behaviour is another anomaly.

By: Josh Brown

Josh Brown — Thu, 14 Jan 2010 13:03:18 +0000

This is great! I never thought about using “in” in a findAll – thanks for posting!

By: Dierk König

Dierk König — Thu, 14 Jan 2010 12:42:56 +0000

Cool post!
One should mention that ‘in’ is based on the isCase() method and is thus available for _any_ object and adaptable to ones needs.
if (x in Float)
if (x in ~/regex/)
etc.

see also Groovy in Action, second edition.

By: John Rellis

John Rellis — Thu, 14 Jan 2010 10:46:52 +0000

Thanks Peter! You are right when you say “For many people…”… now there’s one less person! Gotta love it!