1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
// $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 float:
assert(x == 7.4 && i == Float, "float");
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");
}
}
|
