Trait StaticDowncast

pub trait StaticDowncast<T>: Sized {
    // Required method
    unsafe fn static_downcast(ptr: Ptr<Self>) -> Ptr<T>;
}

Converts a class pointer to a base class pointer without a runtime check.

A null pointer is always converted to a null pointer. Otherwise, the provided pointer must be valid and point to the object of the specified type.

It’s generally safer to use DynamicCast instead because it performs a checked conversion. This trait should only be used if the type of the object is known.

It’s recommended to perform the conversion by calling static_downcast method on pointer types (CppBox, Ptr, Ref) instead of importing the trait directly.

Provides access to C++ static_cast conversion from base class to derived class. The conversion in opposite direction can be done with StaticUpcast.

If T1 class is derived (in C++) from T2 class (directly or indirectly), StaticDowncast<T1> is implemented for T2. The implementation is generated by ritual automatically.

Note that Rust functions associated with this trait have runtime overhead. In C++, static_cast is usually a no-op if there is no multiple inheritance, and multiple inheritance requires pointer adjustment. However, Rust compiler and ritual do not have any information about these implementation details, so all calls of static_cast are wrapper in FFI functions.

Required Methods

unsafe fn static_downcast(ptr: Ptr<Self>) -> Ptr<T>

Convert type of a const pointer.

Safety

This operation is safe as long as ptr is either null or points to an object of the T class or a class inherited by 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