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android / platform / external / rust / crates / downcast / 70259aaf25cdfa3eb845d01e41589a22f4035eb9
commit70259aaf25cdfa3eb845d01e41589a22f4035eb9[log] [tgz]
authorJames Farrell <[email protected]>Tue May 21 15:04:10 2024 +0000
committerAutomerger Merge Worker <[email protected]>Tue May 21 15:04:10 2024 +0000
tree2ed307f637804d94ea18b6a3a96038c19f43f839
parente5ba7accff5147f85f948363081653d14d86974d [diff]
parentef75a6ca7b8778646f5d5e1563efe9a8c0dc357f [diff]
Update Android.bp by running cargo_embargo am: 616aa4e37b am: ef75a6ca7b

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/downcast/+/3095558

Change-Id: I45a3689c7dc0ecd8c10d4fc352475fb223c3d465
Signed-off-by: Automerger Merge Worker <[email protected]>
tree: 2ed307f637804d94ea18b6a3a96038c19f43f839
  1. examples/
  2. src/
  3. tests/
  4. LICENSE ⇨ LICENSE-MIT
  5. .cargo_vcs_info.json
  6. .gitattributes
  7. .gitignore
  8. Android.bp
  9. Cargo.toml
  10. cargo_embargo.json
  11. clippy.toml
  12. LICENSE-MIT
  13. METADATA
  14. MODULE_LICENSE_MIT
  15. OWNERS
  16. README.md
README.md

downcast   Latest Version

A trait (& utilities) for downcasting trait objects back to their original types.

link to API documentation

example usage

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 Arc-pointers.

build features

  • std (default) enables all functionality requiring the standard library (Downcast::downcast()).
  • nightly enables all functionality requiring rust nightly (Any::type_name()).

faq

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, Any for Downcast and AnySync for DowncastSync.

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!