scala> case class ContAB[A,B](a:A, b:B)

scala> implicit def cabTOpab[A,B, CC <% ContAB[A,B]](cc: CC):
     |     (A, B) = {
     |   val contab: ContAB[A,B] = cc
     |   (contab.a, contab.b)
     | }

scala> ContAB(1, "YO"): (Int, String)
<console>:8: error: type mismatch;
 found   : ContAB[Int,java.lang.String]
 required: (Int, String)
       ContAB(0, "Yo"): (Int, String)

scala> cabTOpab(ContAB(1, "Yo"))
res3: (Int, java.lang.String) = (1,Yo)

scala> case class ContAB[A,B](a:A, b:B)
defined class ContAB

scala> implicit def cabTOpab[A,B](cab: ContAB[A,B]): (A,B) = {
     |   (cab.a, cab.b)
     | }
cabTOpab: [A,B](cab: ContAB[A,B])(A, B)

scala> ContAB(1, "Yo"): (Int, String)
res0: (Int, String) = (1,Yo)

scala> case class ContABC[A,B,C](a:A, b:B, c:C)
defined class ContABC

scala> implicit def cabcTOt3[A,B,C, CC <% ContABC[A,B,C]](cc: CC): (A,B,C) = {
     |   val cabc: ContABC[A,B,C] = cc
     |   (cabc.a, cabc.b, cabc.c)
     | }
cabcTOt3: [A,B,C,CC](cc: CC)(implicit evidence$$1: (CC) => ContABC[A,B,C])(A, B,
C)

scala> ContABC(1, "YO", 0.0): (Int, String, Double)
<console>:8: error: type mismatch;
 found   : ContABC[Int,java.lang.String,Double]
 required: (Int, String, Double)
       ContABC(1, "YO", 0.0): (Int, String, Double)
              ^

scala> case class ContABC[A,B,C](a:A, b:B, c:C)
defined class ContABC

scala> implicit def t3abcTOcabc[A,B,C, CC <% (A,B,C)](cc: CC): ContABC[A,B,C] =
{
     |   val t3abc: (A,B,C) = cc
     |   ContABC(t3abc._1, t3abc._2, t3abc._3)
     | }
t3abcTOcabc: [A,B,C,CC](cc: CC)(implicit evidence$$1: (CC) => (A, B, C))ContABC[A,B,C]

scala> (1, "Yo", 0.0): ContABC[Int, String, Double]
res0: ContABC[Int,String,Double] = ContABC(1,Yo,0.0)