Trait com_scrape_types::Inherits
source · pub unsafe trait Inherits<I: Interface>: Interface { }Expand description
Represents the “is-a” relationship for interfaces.
If interface I implements Inherits<J>, it is valid to cast a pointer of type *mut I to a
pointer of type *mut J and to call any of J’s methods via that pointer.
The Inherits relation should be reflexive and transitive, i.e. I: Inherits<I> should be
true for any type I, and if I: Inherits<J> and J: Inherits<K> are true, then
I: Inherits<K> should also be true. However, this is not a safety requirement.
§Safety
Interface is a supertrait of Inherits, so all of Interface’s safety requirements also
apply to Inherits. In particular, if I implements Inherits, it must have the same layout
as the pointer type *const I::Vtbl.
If I implements Inherits<J>, then the layout of J::Vtbl must be a prefix of the layout of
I::Vtbl, i.e. a valid pointer to an instance of I::Vtbl must also be a valid pointer to an
instance of J::Vtbl.