Crate ptr_meta

A radioactive stabilization of the ptr_meta RFC.

Usage

Sized types

All Sized types have Pointee implemented for them with a blanket implementation. You do not need to derive Pointee for these types.

slices and strs

These core types have implementations built in.

dyn Any

The trait object for this standard library type comes with an implementation built in.

Structs with a DST as its last field

You can derive Pointee for structs with a trailing DST:

use ptr_meta::Pointee;

#[derive(Pointee)]
struct Block<H, T> {
    header: H,
    elements: [T],
}

Note that this will only work when the last field is guaranteed to be a DST. Structs with a generic last field may have a conflicting blanket impl since the generic type may be Sized. In these cases, a collection of specific implementations may be required with the generic parameter set to a slice, str, or specific trait object.

Trait objects

You can generate a Pointee implementation for trait objects:

use ptr_meta::pointee;

// Generates Pointee for dyn Stringy
#[pointee]
trait Stringy {
    fn as_string(&self) -> String;
}

Structs

• DynMetadata
  The metadata for a Dyn = dyn SomeTrait trait object type.

Traits

• NonNullExt
  Extension methods for NonNull.
• Pointee
  Provides the pointer metadata type of any pointed-to type.
• PtrExt
  Extension methods for pointers.

Functions

• from_raw_parts
  Forms a (possibly wide) raw pointer from a data address and metadata.
• from_raw_parts_mut
  Performs the same functionality as from_raw_parts, except that a raw *mut pointer is returned, as opposed to a raw *const pointer.
• metadata
  Returns the metadata component of a pointer.

Attribute Macros

• pointee
  Generates an implementation of Pointee for trait objects.

Derive Macros

• Pointee
  Generates an implementation of Pointee for structs with a DST as its last field.