Trait Superclass 

pub unsafe trait Superclass: Sized {
    // Required method
    fn vmt_rva() -> Rva;

    // Provided methods
    fn vmt_va() -> Va { ... }
    fn vmt(&self) -> Va { ... }
    fn is_subclass<T: Subclass<Self>>(&self) -> bool { ... }
    fn as_subclass<T: Subclass<Self>>(&self) -> Option<&T> { ... }
    fn as_subclass_mut<T: Subclass<Self>>(&mut self) -> Option<&mut T> { ... }
}

A trait for C++ types that have multiple different subclasses. Implementing this for a superclass and Subclass for its subclasses makes it possible to safely check for the object’s actual type based on its vtable.

Safety

In order to implement this for a struct, you must guarantee:

• The struct uses C-style layout.
• The first element of the struct is a pointer to a C++-style vtable.
• There’s a 1-to-1 correspondence between vtable address and C++ class.

Required Methods

fn vmt_rva() -> Rva

The RVA of this class’s virtual method table.

Provided Methods

fn vmt_va() -> Va

The VA of this class’s virtual method table.

fn vmt(&self) -> Va

Returns the Va for the runtime virtual method table for this.

fn is_subclass<T: Subclass<Self>>(&self) -> bool

Returns whether this is an instance of T.

Note: Because this just checks the address of the virtual method table, it will return false for subclasses of T even though C++ considers them to be of type T.

fn as_subclass<T: Subclass<Self>>(&self) -> Option<&T>

Returns this as a T if it is one. Otherwise, returns None.

Note: Because this just checks the address of the virtual method table, it will return None for subclasses of T even though C++ considers them to be of type T.

fn as_subclass_mut<T: Subclass<Self>>(&mut self) -> Option<&mut T>

Returns this as a mutable T if it is one. Otherwise, returns None.

Note: Because this just checks the address of the virtual method table, it will return None for subclasses of T even though C++ considers them to be of type T.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors