| // $G $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. |
| |
| package main |
| |
| import "os" |
| |
| const ( |
| Bool = iota |
| Int |
| Float |
| String |
| Struct |
| Chan |
| Array |
| Map |
| Func |
| Last |
| ) |
| |
| type S struct { |
| a int |
| } |
| |
| var s S = S{1234} |
| |
| var c = make(chan int) |
| |
| var a = []int{0, 1, 2, 3} |
| |
| var m = make(map[string]int) |
| |
| func assert(b bool, s string) { |
| if !b { |
| println(s) |
| os.Exit(1) |
| } |
| } |
| |
| func f(i int) interface{} { |
| switch i { |
| case Bool: |
| return true |
| case Int: |
| return 7 |
| case Float: |
| return 7.4 |
| case String: |
| return "hello" |
| case Struct: |
| return s |
| case Chan: |
| return c |
| case Array: |
| return a |
| case Map: |
| return m |
| case Func: |
| return f |
| } |
| panic("bad type number") |
| } |
| |
| func main() { |
| for i := Bool; i < Last; i++ { |
| switch x := f(i).(type) { |
| case bool: |
| assert(x == true && i == Bool, "bool") |
| case int: |
| assert(x == 7 && i == Int, "int") |
| case float64: |
| assert(x == 7.4 && i == Float, "float64") |
| case string: |
| assert(x == "hello" && i == String, "string") |
| case S: |
| assert(x.a == 1234 && i == Struct, "struct") |
| case chan int: |
| assert(x == c && i == Chan, "chan") |
| case []int: |
| assert(x[3] == 3 && i == Array, "array") |
| case map[string]int: |
| assert(x == m && i == Map, "map") |
| case func(i int) interface{}: |
| assert(x == f && i == Func, "fun") |
| default: |
| assert(false, "unknown") |
| } |
| } |
| |
| // boolean switch (has had bugs in past; worth writing down) |
| switch { |
| case true: |
| assert(true, "switch 2 bool") |
| default: |
| assert(false, "switch 2 unknown") |
| } |
| |
| switch true { |
| case true: |
| assert(true, "switch 3 bool") |
| default: |
| assert(false, "switch 3 unknown") |
| } |
| |
| switch false { |
| case false: |
| assert(true, "switch 4 bool") |
| default: |
| assert(false, "switch 4 unknown") |
| } |
| |
| } |