Implicit conversion for multiple parameters

Question

Is it possible to implement in Scala an implicit conversion for the group of parameters (without defining them as some class member) like

implicit def triple2One (x :Int, s :String, d :Double) =  x  // just as an example

So that I would be able to call it in the code like

val x :Int = (1, "test", 2.0)

From your example, I think that closest you can get to the desired result is by defining an implicit conversion for Tuple3[Int, String, Double] (can also be short-handed in the argument as arg : (Int, String, Double))... — Patryk Ćwiek
– Patryk Ćwiek, Commented Nov 29, 2013 at 17:16

Randall Schulz · Accepted Answer · 2013-11-29 22:59:58Z

3

It is possible:

scala> implicit def iFromISD(isd: (Int, String, Double)): Int = isd._1
iFromISD: (isd: (Int, String, Double))Int

scala> val x: Int = (1, "two", 3.0)
x: Int = 1

Naturally, there has to be a type annotation on the resulting val to drive the search for and application of the implicit conversion.

Addendum

It occurs to me there's another way that doesn't involve dubious implicit conversions:

scala> val (y, _, _) = (1, "two", 3.0)
y: Int = 1

edited Nov 29, 2013 at 22:59

answered Nov 29, 2013 at 17:22

Randall Schulz

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