Crate vtable[−][src]
Expand description
This crate allows you to create ffi-friendly virtual tables.
Features
- A
#[vtable]
macro to annotate a VTable struct to generate the traits and structure to safely work with it. VRef
/VRefMut
/VBox
types. They are fat reference/box types which wrap a pointer to the vtable, and a pointer to the object.VRc
/VWeak
types: equivalent tostd::rc::{Rc, Weak}
types but works with a vtable pointer.- Ability to store constants in a vtable.
- These constants can even be a field offset.
Example of use:
use vtable::*; // we are going to declare a VTable structure for an Animal trait #[vtable] #[repr(C)] struct AnimalVTable { /// pointer to a function that makes a noise. The `VRef<AnimalVTable>` is the type of /// the self object. /// /// Note: the #[vtable] macro will automatically add `extern "C"` if that is missing. make_noise: fn(VRef<AnimalVTable>, i32) -> i32, /// if there is a 'drop' member, it is considered as the destructor. drop: fn(VRefMut<AnimalVTable>), } struct Dog(i32); // The #[vtable] macro created the Animal Trait impl Animal for Dog { fn make_noise(&self, intensity: i32) -> i32 { println!("Wof!"); return self.0 * intensity; } } // the vtable macro also exposed a macro to create a vtable AnimalVTable_static!(static DOG_VT for Dog); // with that, it is possible to instantiate a VBox let animal_box = VBox::<AnimalVTable>::new(Dog(42)); assert_eq!(animal_box.make_noise(2), 42 * 2);
The #[vtable]
macro created the “Animal” trait.
Note that the #[vtable]
macro is applied to the VTable struct so
that cbindgen
can see the actual vtable.
Re-exports
pub use const_field_offset::*;
Macros
Creates a VRef
or a VRefMut
suitable for an instance that implements the trait
Structs
Similar to std::alloc::Layout
, but repr(C)
An equivalent of a Box that holds a pointer to a VTable and a pointer to an instance. A VBox frees the instance when dropped.
Represents an offset to a field of type matching the vtable, within the Base container structure.
A reference counted pointer to an object matching the virtual table T
VRef<'a MyTraitVTable>
can be thought as a &'a dyn MyTrait
VRefMut<'a MyTraitVTable>
can be thought as a &'a mut dyn MyTrait
Traits
Allow to associate a VTable with a type.
Internal trait that is implemented by the #[vtable]
macro.
This trait is implemented by the #[vtable]
macro.
This trait is implemented by the #[vtable]
macro.
Attribute Macros
This macro needs to be applied to a VTable structure