Question

The problem I’ve just faced is what to do in the following case:

func printItems(header string, items []interface{}, fmtString string) {
  // ...
}

func main() {
  var iarr = []int{1, 2, 3}
  var farr = []float{1.0, 2.0, 3.0}
  printItems("Integer array:", iarr, "")
  printItems("Float array:", farr, "")
}

Go has no generics and doesn’t allow to use collection covariance:

prog.go:26: cannot use iarr (type []int) as type []interface { } in function argument      
prog.go:27: cannot use farr (type []float) as type []interface { } in function argument

Ideas?

Answer 1

There’s not really a way to do this right now without either

1. Making your []int and []float both into []interface{}.
2. Making printItems accept interface{} instead of []interface{} and then use reflection, similar to what the fmt package does.

Neither solution is pretty.