Any
Any is a Rust trait that supports runtime type identification and checked conversion of suitable values to concrete types.
Learn Rust in a Month of Lunches
Any is a Rust standard-library trait for values that can support runtime type inspection and downcasting when they satisfy the required lifetime conditions.
- How it is used
- Supports checking a panic payload’s type inside a custom panic hook.
- How deep it goes
- Shows dyn Any + Send and a downcast_ref::<&str>() check, but does not explain trait implementation or lifetime requirements.
- Examples
- Shows a panic hook that prints a borrowed-string payload or “No payload!” when the downcast fails.
- What you can do after
- Apply it via std::panic::set_hook to attempt downcast_ref::<&str>() on a panic payload.
Idiomatic Rust
The Rust Any trait enables runtime type identification and checked conversion to a concrete type for suitable values.
- How it is used
- Enables checked recovery of concrete types from trait objects.
- How deep it goes
- Demonstrates `as_any` and `downcast_ref` without further implementation detail.
- Examples
- Checks trait objects for `MyStruct1` or `MyStruct2` and calls their concrete methods.
- What you can do after
- Apply checked downcasting with `as_any` and `downcast_ref`.
Related concepts
- short-circuit evaluationuses · Short-circuit evaluation is an evaluation strategy that skips remaining operands or processing when the result is already determined.
- findcontrasts with · A find operation searches a collection for the first element or entry matching a value or predicate and returns it, or indicates that no match exists.
- downcast_refproduces · downcast_ref is an operation that attempts to obtain a shared reference to an interface value as a specified concrete type.
- iteratoruses · An iterator is an object or abstraction that provides successive values from a sequence or data source through a traversal protocol.
- panicuses · A panic is a runtime failure mechanism that abruptly stops ordinary execution when an unrecoverable error or violated assumption prevents safe continuation.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.