# Struct core::ptr::DynMetadata
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    pub struct DynMetadata<Dyn: ?Sized> { /* fields omitted */ }

🔬 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

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### impl<Dyn: ?Sized> DynMetadata<Dyn>

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#### pub fn size_of(self) -> usize

🔬 This is a nightly-only experimental API. (`ptr_metadata` #81513)

Returns the size of the type associated with this vtable.

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#### pub fn align_of(self) -> usize

🔬 This is a nightly-only experimental API. (`ptr_metadata` #81513)

Returns the alignment of the type associated with this vtable.

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#### pub fn layout(self) -> Layout

🔬 This is a nightly-only experimental API. (`ptr_metadata` #81513)

Returns the size and alignment together as a `Layout`

## Trait Implementations

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### impl<Dyn: ?Sized> Clone for DynMetadata<Dyn>

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#### fn clone(&self) -> Self

Returns a copy of the value. Read more

1.0.0[src]

#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more

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### impl<Dyn: ?Sized> Debug for DynMetadata<Dyn>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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### impl<Dyn: ?Sized> Hash for DynMetadata<Dyn>

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#### fn hash<H: Hasher>(&self, hasher: &mut H)

Feeds this value into the given `Hasher`. Read more

1.3.0[src]

#### fn hash_slice<H: Hasher>(data: &[Self], state: &mut H) where
Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more

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### impl<Dyn: ?Sized> Ord for DynMetadata<Dyn>

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#### fn cmp(&self, other: &Self) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more

1.21.0[src]

#### fn max(self, other: Self) -> Self where
Self: Sized,

Compares and returns the maximum of two values. Read more

1.21.0[src]

#### fn min(self, other: Self) -> Self where
Self: Sized,

Compares and returns the minimum of two values. Read more

1.50.0[src]

#### fn clamp(self, min: Self, max: Self) -> Self where
Self: Sized,

Restrict a value to a certain interval. Read more

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### impl<Dyn: ?Sized> PartialEq<DynMetadata<Dyn>> for DynMetadata<Dyn>

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#### fn eq(&self, other: &Self) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

1.0.0[src]

#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`.

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### impl<Dyn: ?Sized> PartialOrd<DynMetadata<Dyn>> for DynMetadata<Dyn>

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#### fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more

1.0.0[src]

#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more

1.0.0[src]

#### 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 more

1.0.0[src]

#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more

1.0.0[src]

#### fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more

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### impl<Dyn: ?Sized> Copy for DynMetadata<Dyn>

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### impl<Dyn: ?Sized> Eq for DynMetadata<Dyn>

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### impl<Dyn: ?Sized> Send for DynMetadata<Dyn>

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### impl<Dyn: ?Sized> Sync for DynMetadata<Dyn>

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### impl<Dyn: ?Sized> Unpin for DynMetadata<Dyn>

## Auto Trait Implementations

### impl<Dyn: ?Sized> RefUnwindSafe for DynMetadata<Dyn> where
Dyn: RefUnwindSafe,

### impl<Dyn: ?Sized> UnwindSafe for DynMetadata<Dyn> where
Dyn: UnwindSafe,

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### pub fn type_id(&Self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

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#### pub fn borrow(&Self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

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#### pub fn borrow_mut(&mut Self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

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#### pub fn from(T) -> T

Performs the conversion.

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### impl<T, U> Into<U> for T where
U: From<T>,

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#### pub fn into(Self) -> U

Performs the conversion.

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

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#### pub fn try_from(U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

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#### pub fn try_into(Self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.