20 releases (11 breaking)
|0.11.0||Nov 9, 2021|
|0.10.0||Feb 13, 2019|
|0.9.2||Feb 15, 2018|
|0.9.1||Sep 16, 2017|
|0.2.1||Oct 26, 2015|
#288 in Rust patterns
897,849 downloads per month
Used in 515 crates (14 directly)
A trait (& utilities) for downcasting trait objects back to their original types.
Add to your Cargo.toml:
[dependencies] downcast = "0.12"
Add to your crate root:
#[macro_use] extern crate downcast;
- simple showcases the most simple usage of this library.
- with_params showcases how to deal with traits who have type parameters.
- sync_service showcases how to downcast
- std (default) enables all functionality requiring the standard library (
- nightly enables all functionality requiring rust nightly (
Q: I'm getting
the size for values of type XXX cannot be known at compile time errors, what am i doing wrong?
A: Make sure you use the corresponding
Any bound along with the
Downcast traits. So,
Q: Can i cast trait objects to trait objects?
A: No, that is currently no possible in safe rust - and unsafe solutions are very tricky, as well. If you found a solution, feel free to share it!
Q: What is the difference between this and the
downcast-rs crate on crates.io?
A: At the moment, there isn't one, really. There was an unfortunate naming clash. You may consider using the other crate, as it is more actively maintained. This one is considered feature-complete and frozen in functionality. Hopefully, one day, the Rust language will make downcasting easier and we will need neither of these crates anymore!