5 unstable releases
0.3.0 | Feb 27, 2021 |
---|---|
0.2.2 | Jan 4, 2021 |
0.2.1 | Jan 3, 2021 |
0.2.0 | Jan 3, 2021 |
0.1.0 | Jan 3, 2021 |
#2542 in Rust patterns
270 downloads per month
Used in edsm-dumps-model
13KB
253 lines
type_hash
Generate a hash for a Rust type.
The primary use-case for this crate is for detecting differences in message types between versions of a crate.
The TypeHash
trait is implemented for most built-in types and a derive macro
is provided, for implementing it for your own types.
Examples
use type_hash::TypeHash;
#[derive(TypeHash)]
pub enum Message {
LaunchMissiles { destination: String },
CancelMissiles,
}
fn main() {
let hash = Message::type_hash();
// this will only change if the type definition changes
assert_eq!(hash, 11652809455620829461);
}
Customising derived TypeHash implementations
#[type_hash(foreign_type)]
If a struct field has a foreign type that does not implement TypeHash
, you can
mark it as a foreign type and the derive TypeHash
implementation will use the
name of the type in the hash instead. You need to be a little bit careful here
because a change in the third party crate could change your type in an undetectable
way.
#[derive(TypeHash)]
pub struct MyStruct {
#[type_hash(foreign_type)]
data: ArrayVec<[u16; 7]>
}
#[type_hash(skip)]
Skip a field, so it is not part of the hash.
#[derive(TypeHash)]
pub struct MyStruct {
#[type_hash(skip)]
not_important: Vec<i64>,
}
#[type_hash(as = "...")]
Hash a field as if it had a different type. This allows you to change the type of a field to a different type that is still compatible for your application, without affecting the hash.
#[derive(TypeHash)]
pub struct MyStruct {
#[type_hash(as = "HashSet<i64>")]
numbers: BTreeSet<i64>,
}
Dependencies
~1.5MB
~37K SLoC