builder_derive 0.0.1

A simple proc macro that allows the user to auto generate a simple builder pattern.
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

<h1 align="center">
    builder-derive
</h1>

builder-derive provides two main macros, the builder and consumer macro, this crate mainly exists as a support crate for [disarmv7](https://github.com/ivario123/disarmv7) but could be used outside of that. For most cases, there exist better alternatives such as [`derive_builder`](https://docs.rs/derive_builder/latest/derive_builder/) but that one requires unwraps which, in a builder should not be needed as the type system can guarantee safe construction.

## Examples

### Builder

```rust
use builder_derive::Builder;

#[derive(Builder)]
pub struct CoolStruct {
    field_a: usize,
    field_b: i32
}


let implementation = CoolStruct::builder().set_field_a(2).set_field_b(4).complete();

assert!(implementation.field_a == 2);
assert!(implementation.field_b == 4);
```

If any fields are not specified it will fail.

```compile_fail
use builder_derive::Builder;

#[derive(Builder)]
pub struct CoolStruct {
    field_a: usize,
    field_b: i32
}


let implementation = CoolStruct::builder().set_field_a(2).complete();
```

### Consumer

The consumer pattern is a bit niche but it is useful if you have a bunch of autogenerated structs and want to be certain that you do not miss any cases.

```rust
use builder_derive::{Builder,Consumer};

#[derive(Builder,Consumer,PartialEq)]
pub struct CoolStruct {
    field_a: usize,
    field_b: i32
}


let implementation = CoolStruct::builder().set_field_a(2).set_field_b(4).complete();

assert!(implementation.field_a == 2);
assert!(implementation.field_b == 4);

let consumer = implementation.consumer();
let (field_a,consumer) = consumer.consume_field_a();
let (field_b,consumer) = consumer.consume_field_b();
consumer.consume();
assert!(field_a == 2);
assert!(field_b == 4);
```

If any fields are not consumed it will fail to compile.

```compile_fail
use builder_derive::{Builder,Consumer};

#[derive(Builder,Consumer,PartialEq)]
pub struct CoolStruct {
    field_a: usize,
    field_b: i32
}


let implementation = CoolStruct::builder().set_field_a(2).set_field_b(4).complete();

assert!(implementation.field_a == 2);
assert!(implementation.field_b == 4);

let consumer = implementation.consumer();
let (field_a,consumer) = consumer.consume_field_a();
consumer.consume();
assert!(field_a == 2);
```

## Future extensions

It would be nice with an extension that allows for generics and an extension that allows the user to specify a conversion function that converts into the field type.

## License

This repository is licensed under the [MIT](./LICENSE) license and any contributions shall be licensed under the same license unless explicitly stated otherwise.