smart-default 0.2.0

Rust custom-derive macro for Default with more control on the fields
Documentation 
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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

#[macro_use]
extern crate smart_default;

#[test]
fn test_unit() {
    #[derive(PartialEq, SmartDefault)]
    struct Foo;

    assert!(Foo::default() == Foo);
}

#[test]
fn test_tuple() {
    #[derive(PartialEq, SmartDefault)]
    struct Foo (
        #[default = "10"]
        i32,
        #[default = "20"]
        i32,
        // No default
        i32,
    );

    assert!(Foo::default() == Foo(10, 20, 0));
}

#[test]
fn test_struct() {
    #[derive(PartialEq, SmartDefault)]
    struct Foo {
        #[default = "10"]
        x: i32,
        #[default = "20"]
        y: i32,
        // No default
        z: i32,
    }

    assert!(Foo::default() == Foo { x: 10, y: 20, z: 0 });
}

#[test]
fn test_enum_of_units() {
    #[derive(PartialEq, SmartDefault)]
    pub enum Foo {
        #[allow(dead_code)]
        Bar,
        #[default]
        Baz,
        #[allow(dead_code)]
        Qux,
    }

    assert!(Foo::default() == Foo::Baz);
}

#[test]
fn test_enum_of_tuples() {
    #[derive(PartialEq, SmartDefault)]
    pub enum Foo {
        #[allow(dead_code)]
        Bar(i32),
        #[default]
        Baz(#[default = "10"] i32, i32),
        #[allow(dead_code)]
        Qux(i32),
    }

    assert!(Foo::default() == Foo::Baz(10, 0));
}

#[test]
fn test_enum_of_structs() {
    #[derive(PartialEq, SmartDefault)]
    pub enum Foo {
        #[allow(dead_code)]
        Bar {
            x: i32,
        },
        #[default]
        Baz {
            #[default = "10"]
            y: i32,
            z: i32,
        },
        #[allow(dead_code)]
        Qux {
            w: i32,
        },
    }

    assert!(Foo::default() == Foo::Baz { y: 10, z: 0 });
}

#[test]
fn test_enum_mixed() {
    #[derive(PartialEq, SmartDefault)]
    enum Foo {
        #[allow(dead_code)]
        Bar,
        #[default]
        Baz(#[default = "10"] i32),
        #[allow(dead_code)]
        Qux {
            w: i32,
        },
    }

    assert!(Foo::default() == Foo::Baz(10));
}

#[test]
fn test_generics_type_parameters() {
    #[derive(PartialEq, SmartDefault)]
    struct Foo<T> where T: Default {
        #[default = "Some(Default::default())"]
        x: Option<T>
    }

    assert!(Foo::default() == Foo { x: Some(0) });
}

#[test]
fn test_generics_lifetime_parameters() {
    // NOTE: A default value makes no sense with lifetime parameters, since ::default() receives no
    // paramters and therefore can receive no lifetimes. But it does make sense if you make a variant
    // without ref fields the default.

    #[derive(PartialEq, SmartDefault)]
    enum Foo<'a> {
        #[default]
        Bar(i32),
        #[allow(dead_code)]
        Baz(&'a str)
    }

    assert!(Foo::default() == Foo::Bar(0));
}