blob: f15f5ef0fb3f054173fdf08b38d502ef036428d5 [file] [log] [blame]
// $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" {
panic("not hello: ", s);
}
}
func five(i int) {
if i != 5 {
panic("not 5: ", i);
}
}
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
var u1 U;
u1, 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);
}