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Test demonstrating extension method shorthands #6339

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Apr 19, 2019
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Test demonstrating extension method shorthands #6339

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eefe66f
Test demonstrating extension method shorthands
odersky Apr 18, 2019
3eb8a78
Fix test
odersky Apr 18, 2019
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17 changes: 17 additions & 0 deletions tests/run/extmethods2.scala
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object Test extends App {

class TC

implied StringListOps given TC {
type T = List[String]
def (x: T) foo (y: T) = (x ++ y, the[TC])
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It's an interesting trick, but I'm afraid that it'll make signature information less readable in error messages and in the IDE (e.g. if I'm writing a.foo(, then a signature popup will tell me that an argument of type T is expected), and dealiasing all the time before showing type information is likely to be even less readable in general.

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Well, in practice it would probably be named This or Self or Left, not T. And of course we should have defined foo like this:

def (x: T) foo (y: List[String]) = ...

Then the signature popup gives you the right info again.

def (x: T) bar (y: Int) = (x(0)(y), the[TC])
}

def test given TC = {
assert(List("abc").foo(List("def"))._1 == List("abc", "def"))
assert(List("abc").bar(2)._1 == 'c')
}

test given TC()
}