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// $G $D/$F.go && $L $F.$A && ./$A.out
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Check uses of all the different interface
// conversion runtime functions.
package main
type Stringer interface {
String() string
}
type StringLengther interface {
String() string
Length() int
}
type Empty interface{}
type T string
func (t T) String() string {
return string(t)
}
func (t T) Length() int {
return len(t)
}
type U string
func (u U) String() string {
return string(u)
}
var t = T("hello")
var u = U("goodbye")
var e Empty
var s Stringer = t
var sl StringLengther = t
var i int
var ok bool
func hello(s string) {
if s != "hello" {
println("not hello: ", s)
panic("fail")
}
}
func five(i int) {
if i != 5 {
println("not 5: ", i)
panic("fail")
}
}
func true(ok bool) {
if !ok {
panic("not true")
}
}
func false(ok bool) {
if ok {
panic("not false")
}
}
func main() {
// T2I
s = t
hello(s.String())
// I2T
t = s.(T)
hello(t.String())
// T2E
e = t
// E2T
t = e.(T)
hello(t.String())
// T2I again
sl = t
hello(sl.String())
five(sl.Length())
// I2I static
s = sl
hello(s.String())
// I2I dynamic
sl = s.(StringLengther)
hello(sl.String())
five(sl.Length())
// I2E (and E2T)
e = s
hello(e.(T).String())
// E2I
s = e.(Stringer)
hello(s.String())
// I2T2 true
t, ok = s.(T)
true(ok)
hello(t.String())
// I2T2 false
_, ok = s.(U)
false(ok)
// I2I2 true
sl, ok = s.(StringLengther)
true(ok)
hello(sl.String())
five(sl.Length())
// I2I2 false (and T2I)
s = u
sl, ok = s.(StringLengther)
false(ok)
// E2T2 true
t, ok = e.(T)
true(ok)
hello(t.String())
// E2T2 false
i, ok = e.(int)
false(ok)
// E2I2 true
sl, ok = e.(StringLengther)
true(ok)
hello(sl.String())
five(sl.Length())
// E2I2 false (and T2E)
e = u
sl, ok = e.(StringLengther)
false(ok)
}
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