[−][src]Trait cpp_core::StaticDowncast
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.