Struct serde::lib::core::ptr::DynMetadata

source ·
pub struct DynMetadata<Dyn>where
    Dyn: ?Sized,
{ vtable_ptr: &'static VTable, phantom: PhantomData<Dyn>, }
🔬This is a nightly-only experimental API. (ptr_metadata)
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.

Fields

vtable_ptr: &'static VTable
🔬This is a nightly-only experimental API. (ptr_metadata)
phantom: PhantomData<Dyn>
🔬This is a nightly-only experimental API. (ptr_metadata)

Implementations

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

Returns the size of the type associated with this vtable.

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

Returns the alignment of the type associated with this vtable.

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

Returns the size and alignment together as a Layout

Trait Implementations

Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
This method returns an Ordering between self and other. Read more
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.