Struct Meta 

pub struct Meta { /* private fields */ }

Stores fat pointer metadata in a type-erased way.

Used internally by MultiAny to safely downcast to concrete types or trait objects.

Fields

• meta_raw: Raw metadata pointer stored as usize.
• data_id: TypeId of the original data type.
• meta_id: TypeId of the metadata type.

Safety

• meta_raw must have been created from a DynMetadata<T> or ().
• data_id and meta_id must match the data and metadata types exactly.

Implementations

impl Meta

pub fn try_from<Data, RequestedType>( data: &Data, requested_type_id: TypeId, cast_fn: fn(&Data) -> &RequestedType, ) -> Option<Meta>

where Data: 'static, RequestedType: Pointee + ?Sized + 'static, RequestedType::Metadata: TypedMetadata,

Attempts to construct Meta for a requested type.

Parameters

• data: Reference to the concrete data.
• requested_type_id: TypeId of the requested type.
• cast_fn: Function to cast &Data to &RequestedType.

Returns

• Some(Meta) if requested_type_id matches RequestedType.
• None otherwise.

Type Parameters

• Data: Concrete type stored in the MultiAny.
• RequestedType: Type to attempt downcasting to.

pub fn into_metadata<Data, RequestedType>(self) -> RequestedType::Metadata

where Data: 'static, RequestedType: Pointee + ?Sized + 'static, RequestedType::Metadata: TypedMetadata,

Converts this Meta into the concrete metadata type for a requested type.

Type Parameters

• Data: The concrete type stored in the MultiAny.
• RequestedType: The type whose metadata you want to reconstruct.

Returns

The metadata of type RequestedType::Metadata.