Reinventing From Scratch — Unique Pointers in Rust (Historical & Practical)

Chapter 0 — Preface

Unique<T> used to exist in core::ptr as a marker that a pointer was non-null and uniquely owned (no aliasing). Today, NonNull<T> covers the non-null aspect, and uniqueness is expressed via APIs and lifetimes. This book reconstructs the ideas behind Unique so you can encode them explicitly in your containers.

Reinventing From Scratch — Unique Pointers in Rust (Historical & Practical)

Chapter 0 — Preface

Unique<T> used to exist in core::ptr as a marker that a pointer was non-null and uniquely owned (no aliasing). Today, NonNull<T> covers the non-null aspect, and uniqueness is expressed via APIs and lifetimes. This book reconstructs the ideas behind Unique so you can encode them explicitly in your containers.

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}

title: “Unique Pointers in Rust: Encoding Non-Null + No-Alias” meta_description: “Deep-dive on uniqueness and aliasing in Rust: design patterns for containers, provenance, guards, FFI transfers, and tests.” keywords: [“rust unique”, “noalias rust”, “provenance rust”, “nonnull unique”, “vec internals rust”, “panic safety rust”, “miri aliasing”]

Extended Deep Dive

• Formal invariants for exclusive access and how they relate to &mut guarantees.
• Lifetimes as capability tokens: when a borrow exists, unique methods are disabled.
• Using PhantomData to influence variance and auto traits, encoding that your type is invariant over T when necessary.
• Building UniqueBuf<T>: API surfaces that never hand out aliases concurrently.
• Recovery from panics with scope guards; proof sketches that len/cap invariants remain true.

Reference Snippets

use std::{ptr::NonNull, marker::PhantomData};

pub struct UniqueBuf<T> {
    ptr: NonNull<T>,
    len: usize,
    cap: usize,
    _uniq: PhantomData<&'static mut T>, // encodes "unique" at type level
}