Struct abi_stable::prefix_type::WithMetadata_

#[repr(C)]pub struct WithMetadata_<T, P> {
    pub metadata: PrefixMetadata<T, P>,
    pub value: T,
    // some fields omitted
}

Wraps a type along with its prefix-type-related metadata, so that it can be converted to its prefix.

Example

This example demonstrates how you can construct a WithMetadata and convert it to a prefix type pointer (Module_Ref in this case).

You can look at the PrefixRef docs for a more detailed example.

use abi_stable::{
    for_examples::{Module, Module_Ref},
    prefix_type::{PrefixRef, PrefixTypeTrait, WithMetadata},
    std_types::{RSome, RStr},
    staticref,
};
 
// The `staticref` invocation here declares a `StaticRef<WithMetadata<Module>>` constant.
staticref!{const WITH_META: WithMetadata<Module> = WithMetadata::new(
    PrefixTypeTrait::METADATA,
    Module {
        first: RSome(66),
        second: RStr::from_str("lore"),
        third: 333,
    },
)}
 
const MOD: Module_Ref = Module_Ref(WITH_META.as_prefix());
 
assert_eq!(MOD.first(), RSome(66));
assert_eq!(MOD.second().as_str(), "lore");
 

Fields

metadata: PrefixMetadata<T, P>

value: T

The wrapped value.

Implementations

impl<T, P> WithMetadata_<T, P>

pub const fn new(metadata: PrefixMetadata<T, P>, value: T) -> Self

Constructs this with WithMetadata::new(PrefixTypeTrait::METADATA, value)

This takes in the metadata: PrefixMetadata<T> parameter as a workaround for const fn not allowing trait bounds, which in this case is PrefixTypeTrait.

pub const unsafe fn raw_as_prefix(this: *const Self) -> PrefixRef<P>

Constructs a PrefixRef from this.

Safety

You must enture that this WithMetadata lives for the entire program's lifetime.

pub const unsafe fn as_prefix(&self) -> PrefixRef<P>

Constructs a PrefixRef from self.

Safety

You must ensure that self lives for the entire program's lifetime.

Alternative

For a safe equivalent of this, you can use StaticRef::as_prefix.

pub const fn static_as_prefix(&'static self) -> PrefixRef<P>

Constructs a PrefixRef from self.

Example

use abi_stable::{
    for_examples::{Module, Module_Ref},
    prefix_type::{PrefixRef, PrefixTypeTrait, WithMetadata},
    std_types::{RSome, RStr},
};
 
const WITH_META: &WithMetadata<Module> = &WithMetadata::new(
    PrefixTypeTrait::METADATA,
    Module {
        first: RSome(13),
        second: RStr::from_str("foo"),
        third: 100,
    },
);
 
const MOD: Module_Ref = Module_Ref(WITH_META.static_as_prefix());
 
assert_eq!(MOD.first(), RSome(13));
assert_eq!(MOD.second().as_str(), "foo");