lang (traits | operator)
Index should be split into Index and IndexMut.
Currently, the Index trait is not suitable for most array indexing tasks. The slice functionality cannot be replicated using it, and as a result the new Vec has to use .get() and .get_mut() methods.
Additionally, this simply follows the Deref/DerefMut split that has been implemented for a while.
We split Index into two traits (borrowed from @nikomatsakis):
// self[element] -- if used as rvalue, implicitly a deref of the result
trait Index<E,R> {
fn index<'a>(&'a self, element: &E) -> &'a R;
}
// &mut self[element] -- when used as a mutable lvalue
trait IndexMut<E,R> {
fn index_mut<'a>(&'a mut self, element: &E) -> &'a mut R;
}
The number of lang. items increases.
This design doesn't support moving out of a vector-like object. This can be added backwards compatibly.
This design doesn't support hash tables because there is no assignment operator. This can be added backwards compatibly.
The impact of not doing this is that the [] notation will not be available to Vec.
None that I'm aware of.