From Magnet Pattern article, I found implicit conversion special pattern.
What is interesting is that this approach also works for “overloads” with more than one parameter just as well as different return types. If you call complete with several arguments the compiler looks for an implicit conversion that can produce a magnet instance from a tuple wrapping all arguments. This way overloads with up to 22 parameters (the maximum arity of tuples in scala) can be supported.
scala> def printInt(i: Int) = println(i)
printInt: (i: Int)Unit
scala> printInt(10)
10
scala> printInt(10, 20)
^
error: too many arguments (2) for method printInt: (i: Int)Unit
scala> implicit def toOneInt(is: (Int, Int)): Int = is._1 + is._2
warning: there was one feature warning; for details, enable `:setting -feature' or `:replay -feature'
toOneInt: (is: (Int, Int))Int
scala> printInt((10, 20))
30
scala> printInt(10, 20)
30
printInt((10, 20))
is boring me, but printInt(10, 20)
is awesome!
Then I sought the specification of this special pattern from Scala Language Specification (2.12). However I cannot find it yet and finally give up.
Could anyone show me where is the special pattern from Scala Language Specification (2.12) ?