mirror of
https://github.com/golang/go
synced 2024-11-25 00:57:59 -07:00
00f9f0c056
note that sortmain.go has been run through hg gofmt; only the formatting of the day initializers changed. i'm happy to revert that formatting if you'd prefer. stop on error in doc/progs/run R=r CC=golang-dev https://golang.org/cl/850041
148 lines
1.9 KiB
Go
148 lines
1.9 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Check uses of all the different interface
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// conversion runtime functions.
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package main
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type Stringer interface {
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String() string
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}
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type StringLengther interface {
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String() string
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Length() int
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}
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type Empty interface{}
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type T string
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func (t T) String() string {
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return string(t)
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}
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func (t T) Length() int {
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return len(t)
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}
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type U string
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func (u U) String() string {
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return string(u)
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}
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var t = T("hello")
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var u = U("goodbye")
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var e Empty
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var s Stringer = t
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var sl StringLengther = t
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var i int
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var ok bool
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func hello(s string) {
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if s != "hello" {
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println("not hello: ", s)
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panic("fail")
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}
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}
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func five(i int) {
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if i != 5 {
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println("not 5: ", i)
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panic("fail")
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}
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}
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func true(ok bool) {
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if !ok {
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panic("not true")
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}
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}
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func false(ok bool) {
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if ok {
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panic("not false")
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}
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}
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func main() {
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// T2I
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s = t
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hello(s.String())
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// I2T
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t = s.(T)
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hello(t.String())
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// T2E
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e = t
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// E2T
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t = e.(T)
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hello(t.String())
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// T2I again
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sl = t
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hello(sl.String())
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five(sl.Length())
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// I2I static
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s = sl
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hello(s.String())
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// I2I dynamic
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sl = s.(StringLengther)
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hello(sl.String())
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five(sl.Length())
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// I2E (and E2T)
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e = s
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hello(e.(T).String())
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// E2I
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s = e.(Stringer)
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hello(s.String())
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// I2T2 true
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t, ok = s.(T)
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true(ok)
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hello(t.String())
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// I2T2 false
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_, ok = s.(U)
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false(ok)
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// I2I2 true
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sl, ok = s.(StringLengther)
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true(ok)
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hello(sl.String())
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five(sl.Length())
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// I2I2 false (and T2I)
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s = u
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sl, ok = s.(StringLengther)
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false(ok)
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// E2T2 true
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t, ok = e.(T)
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true(ok)
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hello(t.String())
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// E2T2 false
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i, ok = e.(int)
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false(ok)
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// E2I2 true
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sl, ok = e.(StringLengther)
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true(ok)
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hello(sl.String())
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five(sl.Length())
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// E2I2 false (and T2E)
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e = u
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sl, ok = e.(StringLengther)
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false(ok)
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}
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