# gin-tonic
`gin-tonic` offers:
- a protobuf de-/serialization (like [`prost`](http://docs.rs/prost))
- a replacement for [`prost-build`](http://docs.rs/prost-build))
- a [`tonic`](http://docs.rs/tonic) codec implementation
- a wrapper for [`tonic-build`](http://docs.rs/tonic-build) adding some extra extra features
While all this can be achieved using the mentioned crates; `gin-tonic` also offers traits for
converting any Rust type into a protobuf wire type. You are asking why?
If you want to pass a UUID via protobuf you likely end up doing:
```protobuf
message Foo {
string my_uuid = 1;
}
```
Using [`prost-build`](http://docs.rs/prost-build) and [`tonic-build`](http://docs.rs/tonic-build) this will
generate the following Rust struct:
```rust
struct Foo {
my_uuid: String,
}
```
As you notice the Rust type here is `String`, but in your actual code you want to use an actual
[`uuid::Uuid`](docs.rs/uuid). Now you have to do a fallible conversion into your code.
`gin-tonic` solves this by adding options to the protobuf file:
```protobuf
import "gin/proto/gin.proto";
message Foo {
string my_uuid = 1 [(gin_tonic.v1.rust_type) = "uuid::Uuid"];
}
```
Using the `gin-tonic` code generator this generates the following Rust code:
```rust
struct Foo {
my_uuid: uuid::Uuid,
}
```
For the UUID case `gin-tonic` offers two features:
- `uuid_string` => proto transport is `string`, parsing error is handled within wire type conversion
- `uuid_bytes` => proto transport is `bytes`, this does not require additional error handling
You can add you own types by implementing the `FromWire` and `IntoWire` traits for your type.