# Option sets with built-in Serde support
[](https://crates.io/crates/option_set)
[](https://docs.rs/option_set)
[](https://crates.io/crates/option_set)
[](https://github.com/H2CO3/option_set#license)
[](https://github.com/Aaronepower/tokei)
[](http://twitter.com/H2CO3_iOS)
This crate implements a macro `option_set` which knows how to serialize and deserialize itself to/from a sequence of strings. The macro invocation looks very much like [`bitflags!()`](https://doc.rust-lang.org/bitflags/bitflags/index.html), with a few useful additions. In fact, the underlying type *is* generated by the `bitflags!()` macro, therefore you will need the bitflags crate if you are using this library.
## Usage
```
#[macro_use]
extern crate option_set;
#[macro_use]
extern crate bitflags;
extern crate serde;
extern crate serde_json;
option_set! {
struct FooOptions: UpperCamel + u16 {
const BAR_FIRST = 0x0001;
const QUX_SECOND_THING = 0x0080;
const LOL_3RD = 0x4000;
}
}
fn main() {
let opts_in = FooOptions::BAR_FIRST | FooOptions::LOL_3RD;
let json = serde_json::to_string_pretty(&opts_in).unwrap();
println!("{}", json);
let opts_out: FooOptions = serde_json::from_str(&json).unwrap();
println!("{:?}", opts_out);
assert!(opts_out == opts_in);
}
```
In the struct declaration, the first identifier after the colon (`UpperCamel` in the above example) controls how the name of each flag is transformed before serialization. This is necessary because the flags are not real `struct` fields or `enum` variants, so `#[serde(rename_all = "...")]` and the like don't work on them.
The possible name transformations are the variants of the `CaseTransform` enum.
The second type, after the `+` sign, is the underlying type of the bitmask, which is usually an exact-width integer.
## License
MIT