Struct ResourceDynamic 

pub struct ResourceDynamic(/* private fields */);

A host-defined resource in the component model with a dynamic runtime value representing its type.

This type represents a host-owned resource in the same manner as Resource, and almost all of the documentation on that type is applicable to usage of this type as well. Where the two differ is how embedders use these types in a particular embedding.

Use cases for Resource

The Resource type is intended to be used by Rust embedders and provides a T type parameter to provide a layer of type safety when using the resource. The type parameter prevents mixing up resources of the same type by accident. The bindgen! macro, for example, uses Resource by default to represent all resources imported by a wasm guest.

As the documentation on Resource indicates the T type parameter on Resource<T> is a hint and T isn’t stored inside. This means that the host can write a function which takes Resource<T>, for example, and prevent mistakes of passing a wrong-typed-resource to that function. Typically the 32-bit value that Resource<T> wraps is an index into some sort of table the host manages and the index points to a value of type T. The T type parameter can assist in writing helper functions to access these types.

The downside of Resource, however, is that all resource types must be statically assigned at compile time. It’s not possible to manufacture more types at runtime in some more dynamic situations. That’s where ResourceDynamic comes in.

Use cases for ResourceDynamic

The general idea of ResourceDynamic is very similar to Resource – it represents a “trusted” 32-bit value that the host defines and assigns meaning to. There is no destructor on ResourceDynamic and the host has to know how to destroy the associated state, if any, that ResourceDynamic references. The difference with Resource is that is has runtime type information instead of static type information, meaning that it’s possible to mix these up at compile by by accident.

However a ResourceDynamic can be constructed dynamically at runtime with a runtime-defined type. For example an embedding that provides generic access to types in the host may want to take advantage of the dynamic nature of this type. Resources of type ResourceDynamic have a type of [ResourceType::host_dynamic(ty)] where ty is the value provided to the constructors of ResourceDynamic.

A ResourceDynamic implements Lift and Lower in the same manner as Resource, but the implementations may fail after type-checking unlike with Resource (due to the dynamic nature of the type which can’t be fully-checked during type-checking).

Implementations

impl ResourceDynamic

pub fn new_own(rep: u32, ty: u32) -> ResourceDynamic

Creates a new owned resource with the rep specified.

This is the same as Resource::new_own except that ty is an extra parameter for the host-defined type information.

pub fn new_borrow(rep: u32, ty: u32) -> ResourceDynamic

Creates a new borrowed resource which isn’t actually rooted in any ownership.

This is the same as Resource::new_borrow except that ty is an extra parameter for the host-defined type information.

pub fn rep(&self) -> u32

Returns the underlying 32-bit representation used to originally create this resource.

This is the same as Resource::rep.

pub fn ty(&self) -> u32

Returns the 32-bit integer indicating the type of this resource.

This will return the same 32-bit integer provided to the ResourceDynamic::new_own constructor. The meaning of this integer is left to the host and this only serves as an accessor to provide the value back to the host.

pub fn owned(&self) -> bool

Returns whether this is an owned resource or not.

This is the same as Resource::owned.

pub fn try_from_resource_any( resource: ResourceAny, store: impl AsContextMut, ) -> Result<ResourceDynamic, Error>

Attempts to convert a ResourceAny into ResourceDynamic.

This is the same as Resource::try_from_resource_any.

pub fn try_into_resource_any( self, store: impl AsContextMut, ) -> Result<ResourceAny, Error>

See ResourceAny::try_from_resource

Trait Implementations

impl Debug for ResourceDynamic

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

Formats the value using the given formatter.

impl ComponentType for ResourceDynamic

impl Lift for ResourceDynamic

impl Lower for ResourceDynamic