Struct abi_stable::prefix_type::WithMetadata_

#[repr(C)]
pub struct WithMetadata_<T, P> {
    pub value: AlignToUsize<T>,
    /* private fields */
}

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,
};

const WITH_META: &WithMetadata<Module> = &WithMetadata::new(
    Module {
        first: RSome(66),
        second: RStr::from_str("lore"),
        third: 333,
    },
);

const MOD: Module_Ref = Module_Ref(WITH_META.static_as_prefix());

assert_eq!(MOD.first(), RSome(66));
assert_eq!(MOD.second().as_str(), "lore");

Fields

value: AlignToUsize<T>

The wrapped value.

Implementations

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

pub const fn new(value: T) -> Self

where T: PrefixTypeTrait<PrefixFields = P>,

Constructs this with WithMetadata::new(value)

pub const fn field_accessibility(&self) -> FieldAccessibility

A bit array that describes the accessibility of each field in T.

pub const fn type_layout(&self) -> &'static PTStructLayout

The basic layout of the prefix type, for error messages.

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(
    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");