CAD97/pointer-utils

FatErasedPtr

cehteh opened this issue · 0 comments

I had just fun: Type erased pointers that Drop properly:

pub struct FatErasedPtr {
    ptr: ErasedPtr,
    dropfn: fn(ErasedPtr),
}

impl<P: ErasablePtr + 'static> From<P> for FatErasedPtr {
    #[inline(always)]
    fn from(this: P) -> Self {
        fn dropfn<P: ErasablePtr> (this: ErasedPtr) {
            unsafe { <P as ErasablePtr>::unerase(this) };
        }

        FatErasedPtr {
            ptr: P::erase(this),
            dropfn: dropfn::<P>,
        }
    }
}

impl Drop for FatErasedPtr {
    fn drop(&mut self) {
        (self.dropfn)(self.ptr)
    }
}

#[test]
fn faterasedptr() {
    use alloc::rc::Rc;
    let rc: Rc<i32> = Rc::new(123);

    let fat_erased: FatErasedPtr = FatErasedPtr::from(rc);

    assert_eq!(core::mem::size_of_val(&fat_erased), core::mem::size_of::<usize>()*2);
}

Was just a curious experiment here. I can complete that and send a PR if this is interesting.