Generische Methoden
Traits can also be generic, just like types and functions. A trait's parameters get concrete types when it is used.
Speaker Notes
-
The
From
trait will be covered later in the course, but its definition in thestd
docs is simple. -
Implementations of the trait do not need to cover all possible type parameters. Here,
Foo::from("hello")
would not compile because there is noFrom<&str>
implementation forFoo
. -
Generic traits take types as "input", while associated types are a kind of "output" type. A trait can have multiple implementations for different input types.
-
In fact, Rust requires that at most one implementation of a trait match for any type T. Unlike some other languages, Rust has no heuristic for choosing the "most specific" match. There is work on adding this support, called specialization.