1 struct Attr
2 {
3     string name;
4     int value;
5 }
6 
7 @Attr("Answer", 42) int a;
8 static assert(getUDAs!(a, Attr).length == 1);
9 static assert(getUDAs!(a, Attr)[0].name == "Answer");
10 static assert(getUDAs!(a, Attr)[0].value == 42);
11 
12 @(Attr("Answer", 42), "string", 9999) int b;
13 static assert(getUDAs!(b, Attr).length == 1);
14 static assert(getUDAs!(b, Attr)[0].name == "Answer");
15 static assert(getUDAs!(b, Attr)[0].value == 42);
16 
17 @Attr("Answer", 42) @Attr("Pi", 3) int c;
18 static assert(getUDAs!(c, Attr).length == 2);
19 static assert(getUDAs!(c, Attr)[0].name == "Answer");
20 static assert(getUDAs!(c, Attr)[0].value == 42);
21 static assert(getUDAs!(c, Attr)[1].name == "Pi");
22 static assert(getUDAs!(c, Attr)[1].value == 3);
23 
24 static assert(getUDAs!(c, Attr("Answer", 42)).length == 1);
25 static assert(getUDAs!(c, Attr("Answer", 42))[0].name == "Answer");
26 static assert(getUDAs!(c, Attr("Answer", 42))[0].value == 42);
27 
28 static assert(getUDAs!(c, Attr("Answer", 99)).length == 0);
29 
30 struct AttrT(T)
31 {
32     string name;
33     T value;
34 }
35 
36 @AttrT!uint("Answer", 42) @AttrT!int("Pi", 3) @AttrT int d;
37 static assert(getUDAs!(d, AttrT).length == 2);
38 static assert(getUDAs!(d, AttrT)[0].name == "Answer");
39 static assert(getUDAs!(d, AttrT)[0].value == 42);
40 static assert(getUDAs!(d, AttrT)[1].name == "Pi");
41 static assert(getUDAs!(d, AttrT)[1].value == 3);
42 
43 static assert(getUDAs!(d, AttrT!uint).length == 1);
44 static assert(getUDAs!(d, AttrT!uint)[0].name == "Answer");
45 static assert(getUDAs!(d, AttrT!uint)[0].value == 42);
46 
47 static assert(getUDAs!(d, AttrT!int).length == 1);
48 static assert(getUDAs!(d, AttrT!int)[0].name == "Pi");
49 static assert(getUDAs!(d, AttrT!int)[0].value == 3);
50 
51 struct SimpleAttr {}
52 
53 @SimpleAttr int e;
54 static assert(getUDAs!(e, SimpleAttr).length == 1);
55 static assert(is(getUDAs!(e, SimpleAttr)[0] == SimpleAttr));
56 
57 @SimpleAttr() int f;
58 static assert(getUDAs!(f, SimpleAttr).length == 1);
59 static assert(is(typeof(getUDAs!(f, SimpleAttr)[0]) == SimpleAttr));
60 
61 struct FuncAttr(alias f) { alias func = f; }
62 static int add42(int v) { return v + 42; }
63 static string concat(string l, string r) { return l ~ r; }
64 
65 @FuncAttr!add42 int g;
66 static assert(getUDAs!(g, FuncAttr).length == 1);
67 static assert(getUDAs!(g, FuncAttr)[0].func(5) == 47);
68 
69 static assert(getUDAs!(g, FuncAttr!add42).length == 1);
70 static assert(getUDAs!(g, FuncAttr!add42)[0].func(5) == 47);
71 
72 static assert(getUDAs!(g, FuncAttr!add42()).length == 0);
73 
74 static assert(getUDAs!(g, FuncAttr!concat).length == 0);
75 static assert(getUDAs!(g, FuncAttr!concat()).length == 0);
76 
77 @FuncAttr!add42() int h;
78 static assert(getUDAs!(h, FuncAttr).length == 1);
79 static assert(getUDAs!(h, FuncAttr)[0].func(5) == 47);
80 
81 static assert(getUDAs!(h, FuncAttr!add42).length == 1);
82 static assert(getUDAs!(h, FuncAttr!add42)[0].func(5) == 47);
83 
84 static assert(getUDAs!(h, FuncAttr!add42()).length == 1);
85 static assert(getUDAs!(h, FuncAttr!add42())[0].func(5) == 47);
86 
87 static assert(getUDAs!(h, FuncAttr!concat).length == 0);
88 static assert(getUDAs!(h, FuncAttr!concat()).length == 0);
89 
90 @("alpha") @(42) int i;
91 static assert(getUDAs!(i, "alpha").length == 1);
92 static assert(getUDAs!(i, "alpha")[0] == "alpha");
93 
94 static assert(getUDAs!(i, 42).length == 1);
95 static assert(getUDAs!(i, 42)[0] == 42);
96 
97 static assert(getUDAs!(i, 'c').length == 0);