https://github.com/alecmocatta/metatype

Helper methods to work with Rust types.
https://github.com/alecmocatta/metatype

rust slice trait-object types vtable

Last synced: about 1 year ago
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Helper methods to work with Rust types.

• Host: GitHub
• URL: https://github.com/alecmocatta/metatype
• Owner: alecmocatta
• License: apache-2.0
• Created: 2018-07-20T15:37:31.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2025-03-19T16:47:59.000Z (about 1 year ago)
• Last Synced: 2025-03-19T17:38:56.687Z (about 1 year ago)
• Topics: rust, slice, trait-object, types, vtable
• Language: Rust
• Homepage:
• Size: 48.8 KB
• Stars: 2
• Watchers: 1
• Forks: 2
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE.txt

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README

          
# metatype

[![Crates.io](https://img.shields.io/crates/v/metatype.svg?maxAge=86400)](https://crates.io/crates/metatype)

[![MIT / Apache 2.0 licensed](https://img.shields.io/crates/l/metatype.svg?maxAge=2592000)](#License)

[![Build Status](https://dev.azure.com/alecmocatta/metatype/_apis/build/status/tests?branchName=master)](https://dev.azure.com/alecmocatta/metatype/_build?definitionId=7)

[📖 Docs](https://docs.rs/metatype/0.2) | [💬 Chat](https://constellation.zulipchat.com/#narrow/stream/213236-subprojects)

Helper methods to determine whether a type is `TraitObject`, `Slice` or `Concrete`, and work with them respectively.

## Examples

```rust

assert_eq!(usize::METATYPE, MetaType::Concrete);

assert_eq!(any::Any::METATYPE, MetaType::TraitObject);

assert_eq!(<[u8]>::METATYPE, MetaType::Slice);

let a: Box = Box::new(123);

assert_eq!(Type::meta_type(&*a), MetaType::Concrete);

let a: Box = a;

assert_eq!(Type::meta_type(&*a), MetaType::TraitObject);

let a = [123,456];

assert_eq!(Type::meta_type(&a), MetaType::Concrete);

let a: &[i32] = &a;

assert_eq!(Type::meta_type(a), MetaType::Slice);

let a: Box = Box::new(123);

let meta: TraitObject = type_coerce(Type::meta(&*a));

println!("vtable: {:?}", meta.vtable);

```

## Note

This currently requires Rust nightly for the `ptr_metadata`, `specialization` and `arbitrary_self_types_pointers` features.

## License

Licensed under either of

 * Apache License, Version 2.0, ([LICENSE-APACHE.txt](LICENSE-APACHE.txt) or http://www.apache.org/licenses/LICENSE-2.0)

 * MIT license ([LICENSE-MIT.txt](LICENSE-MIT.txt) or http://opensource.org/licenses/MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.