Example
When defining a new trait it is possible to enforce that types wishing to implement this trait verify a number of constraints or bounds.
Taking an example from the standard library, the DerefMut trait requires that a type first implement its sibling Deref trait:
pub trait DerefMut: Deref {
fn deref_mut(&mut self) -> &mut Self::Target;
}
This, in turn, enables DerefMut to use the associated type Target defined by Deref.
While the syntax might be reminiscent of inheritance:
- it brings in all the associated items (constants, types, functions, ...) of the bound trait
- it enables polymorphism from
&DerefMutto&Deref
This is different in nature:
- it is possible to use a lifetime (such as
'static) as a bound - it is not possible to override the bound trait items (not even the functions)
Thus it is best to think of it as a separate concept.
