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(struct{ n int }{}) printItf(struct { n int `foo:"bar"` }{}) 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)) // Try putting a linked list in an interface: // https://github.com/tinygo-org/tinygo/issues/309 itf = linkedList{} } 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 struct{ i int }: println("is struct{i int}") case struct{ n int }: println("is struct{n int}") case struct { n int `foo:"bar"` }: println("is struct{n int `foo:\"bar\"`}") 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() } type linkedList struct { addr *linkedList }