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package main
func main() {
thing := &Thing{"foo"}
println("thing:", thing.String())
thing.Print()
printItf(5)
printItf(byte('x'))
printItf("foo")
printItf(Foo(18))
printItf(*thing)
printItf(thing)
printItf(Stringer(thing))
printItf(Number(3))
array := Array([4]uint32{1, 7, 11, 13})
printItf(array)
printItf(ArrayStruct{3, array})
printItf(SmallPair{3, 5})
s := Stringer(thing)
println("Stringer.String():", s.String())
var itf interface{} = s
println("Stringer.(*Thing).String():", itf.(Stringer).String())
println("nested switch:", nestedSwitch('v', 3))
}
func printItf(val interface{}) {
switch val := val.(type) {
case Unmatched:
panic("matched the unmatchable")
case Doubler:
println("is Doubler:", val.Double())
case Tuple:
println("is Tuple:", val.Nth(0), val.Nth(1), val.Nth(2), val.Nth(3))
val.Print()
case int:
println("is int:", val)
case byte:
println("is byte:", val)
case string:
println("is string:", val)
case Thing:
println("is Thing:", val.String())
case *Thing:
println("is *Thing:", val.String())
case Foo:
println("is Foo:", val)
default:
println("is ?")
}
}
func nestedSwitch(verb rune, arg interface{}) bool {
switch verb {
case 'v', 's':
switch arg.(type) {
case int:
return true
}
}
return false
}
type Thing struct {
name string
}
func (t Thing) String() string {
return t.name
}
func (t Thing) Print() {
println("Thing.Print:", t.name)
}
type Stringer interface {
String() string
}
type Foo int
type Number int
func (n Number) Double() int {
return int(n) * 2
}
type Doubler interface {
Double() int
}
type Tuple interface {
Nth(int) uint32
Print()
}
type Array [4]uint32
func (a Array) Nth(n int) uint32 {
return a[n]
}
func (a Array) Print() {
println("Array len:", len(a))
}
type ArrayStruct struct {
n int
a Array
}
func (a ArrayStruct) Nth(n int) uint32 {
return a.a[n]
}
func (a ArrayStruct) Print() {
println("ArrayStruct.Print:", len(a.a), a.n)
}
type SmallPair struct {
a byte
b byte
}
func (p SmallPair) Nth(n int) uint32 {
return uint32(int(p.a)*n + int(p.b)*n)
}
func (p SmallPair) Print() {
println("SmallPair.Print:", p.a, p.b)
}
// There is no type that matches this method.
type Unmatched interface {
NeverImplementedMethod()
}
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