Struct std::ptr::DynMetadata
source · pub struct DynMetadata<Dyn>where
Dyn: ?Sized,{ /* private fields */ }
🔬This is a nightly-only experimental API. (
ptr_metadata
#81513)Expand description
The metadata for a Dyn = dyn SomeTrait
trait object type.
It is a pointer to a vtable (virtual call table) that represents all the necessary information to manipulate the concrete type stored inside a trait object. The vtable notably it contains:
- type size
- type alignment
- a pointer to the type’s
drop_in_place
impl (may be a no-op for plain-old-data) - pointers to all the methods for the type’s implementation of the trait
Note that the first three are special because they’re necessary to allocate, drop, and deallocate any trait object.
It is possible to name this struct with a type parameter that is not a dyn
trait object
(for example DynMetadata<u64>
) but not to obtain a meaningful value of that struct.
Implementations§
source§impl<Dyn> DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> DynMetadata<Dyn>where
Dyn: ?Sized,
sourcepub fn size_of(self) -> usize
🔬This is a nightly-only experimental API. (ptr_metadata
#81513)
pub fn size_of(self) -> usize
ptr_metadata
#81513)Returns the size of the type associated with this vtable.
Trait Implementations§
source§impl<Dyn> Clone for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Clone for DynMetadata<Dyn>where
Dyn: ?Sized,
source§fn clone(&self) -> DynMetadata<Dyn>
fn clone(&self) -> DynMetadata<Dyn>
Returns a copy of the value. Read more
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from
source
. Read moresource§impl<Dyn> Debug for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Debug for DynMetadata<Dyn>where
Dyn: ?Sized,
source§impl<Dyn> Hash for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Hash for DynMetadata<Dyn>where
Dyn: ?Sized,
source§impl<Dyn> Ord for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Ord for DynMetadata<Dyn>where
Dyn: ?Sized,
source§fn cmp(&self, other: &DynMetadata<Dyn>) -> Ordering
fn cmp(&self, other: &DynMetadata<Dyn>) -> Ordering
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere
Self: Sized,
Compares and returns the maximum of two values. Read more
source§impl<Dyn> PartialEq for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> PartialEq for DynMetadata<Dyn>where
Dyn: ?Sized,
source§fn eq(&self, other: &DynMetadata<Dyn>) -> bool
fn eq(&self, other: &DynMetadata<Dyn>) -> bool
This method tests for
self
and other
values to be equal, and is used
by ==
.source§impl<Dyn> PartialOrd for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> PartialOrd for DynMetadata<Dyn>where
Dyn: ?Sized,
source§fn partial_cmp(&self, other: &DynMetadata<Dyn>) -> Option<Ordering>
fn partial_cmp(&self, other: &DynMetadata<Dyn>) -> Option<Ordering>
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for
self
and other
) and is used by the <=
operator. Read moreimpl<Dyn> Copy for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Eq for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Send for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Sync for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Unpin for DynMetadata<Dyn>where
Dyn: ?Sized,
Auto Trait Implementations§
impl<Dyn> !RefUnwindSafe for DynMetadata<Dyn>
impl<Dyn> !UnwindSafe for DynMetadata<Dyn>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more