Crate detrojt [−] [src]
A hack to support deserialization of arbitrary trait objects.
This an implementation of a workaround for rust-lang/rfcs#668 "Encodable trait objects".
See README.md for the caveats and security implications.
The core of the library rests upon the trio TyConst, get_ty_const, and
get_ty_const_key. They provide a mechanism for looking up data
associated with a type using a persistent identifier ("key").
D: TyConst<T> is a trait used to define such data.
Each implementation associates an arbitrary value of type D
(i.e. Self) with the type parameter T. Conceptually, it's as if every
D has its own table of data, indexed by T. Within a given table,
every T is associated with a unique usize key.
get_ty_const_key returns the unique key for
the data associated with T in the table of D. The key is persistent
(serializable): it can be used in a later execution of the same program.
The key is only guaranteed to be unique for a given D (i.e. the key is
meaningless without knowing what D is).
get_ty_const uses the key to retrieve the data
D associated with T without knowing what T was. If the key is
invalid, then None is returned.
Example
For a more interesting example, see the serde
submodule, which uses TyConst under the hood.
use detrojt::{TyConst, get_ty_const, get_ty_const_key}; #[derive(Debug, PartialEq, Eq)] struct Size(usize); impl<T: 'static> TyConst<T> for Size { fn get_data() -> Self { Size(std::mem::size_of::<T>()) } } assert_eq!(get_ty_const(get_ty_const_key::<Size, ()>()), Some(Size(0))); assert_eq!(get_ty_const(get_ty_const_key::<Size, i64>()), Some(Size(8))); assert_eq!(get_ty_const::<Size>(1), None);
Modules
| serde |
A collection of helper traits that can be used to add serialization support to user-defined traits. |
Traits
| TyConst |
This represents a mapping from a type T to some data of type |
Functions
| get_ty_const |
Get the data in the impl for the type that matches the given key. If the
key is invalid, returns |
| get_ty_const_key |
Get the key associated with |