1/1/2024 0 Comments Downcast rustThis function wants to log its parameter out prior to doing work with it. Box adds the downcast method, which attempts to.Logger function for any type that implements Debug. As &mut Any, there is also the downcastmut method, for getting a mutable reference to the inner value. We don't know the concrete type of our value at compile time, so we need to We want to give special treatment to certain types: in thisĬase printing out the length of String values prior to their value. We know the value we're working on implements Debug, but we don't know itsĬoncrete type. ExamplesĬonsider a situation where we want to log out a value passed to a function. Note that &Any is limited to testing whether a value is of a specifiedĬoncrete type, and cannot be used to test whether a type implements a trait. See the Box documentation for the full details. rfcbot added finished-final-comment-period and removed final-comment-period labels on Jul 7, 2018. bors closed this in 52103 on Jul 6, 2018. Box adds the downcast method, which attempts toĬonvert to a Box. Mark-Simulacrum added a commit to Mark-Simulacrum/rust that referenced this issue on Jul 6, 2018. Is also the downcast_mut method, for getting a mutable reference to the As &Any (a borrowed trait object), it has the is andÄowncast_ref methods, to test if the contained value is of a given type,Īnd to get a reference to the inner value as a type. Of any 'static type through runtime reflection.Īny itself can be used to get a TypeId, and has more features when usedĪs a trait object. It offers core types, like Vec and Option, library-defined operations on language primitives, standard macros, I/O and multithreading, among many other things.This module implements the Any trait, which enables dynamic typing The Rust Standard Library is the foundation of portable Rust software, a set of minimal and battle-tested shared abstractions for the broader Rust ecosystem.
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