Deref
Deref is a Rust standard-library trait that defines how a value is dereferenced to access a target value and enables dereference coercions.
Learn Rust in a Month of Lunches
Deref is the Rust standard trait that defines immutable dereferencing and enables automatic dereference coercions for method and field access.
- How it is used
- Enables wrapper types to expose an inner value’s methods without making the inner field public.
- How deep it goes
- Works through a Deref implementation, method calls, and compiler errors, then distinguishes immutable dereferencing from DerefMut.
- Examples
- Uses a number-holding tuple struct, Box comparison, checked subtraction, and a confusing game-character implementation.
- What you can do after
- Build it from scratch for a simple wrapper, access its target’s methods, and recognize when named methods are clearer.
Idiomatic Rust
Deref is a Rust trait that defines how a value can be dereferenced to access a target value through the dereference operator.
- How it is used
- Enables wrapper structs and smart pointers to expose target methods through dereference coercion.
- How deep it goes
- Works through a wrapper implementation and method-call behavior, then identifies consuming-method and mutable-access limits.
- Examples
- Uses a wrapped vector’s `iter()` and `into_iter()` calls, plus a person wrapper whose `len()` call is misleading.
- What you can do after
- Apply it via Rust’s `Deref` trait to expose appropriate wrapper methods and choose explicit methods or traits when coercion obscures intent.
Related concepts
- deref coercionused by · Deref coercion is Rust's automatic conversion of a reference to a wrapper value into a reference to its dereference target when resolving method calls and compatible operations.
- Cowimplemented by · Cow is Rust’s standard-library clone-on-write type, representing either borrowed or owned data and creating owned data when necessary.
- smart pointerimplemented by · A smart pointer is a pointer-like object that manages or mediates access to a referenced resource, often providing ownership, lifetime, or safety behavior.
- associated typeuses · An associated type is a type member declared by a trait or similar abstraction whose concrete type is specified by each implementation.
- polymorphismuses · Polymorphism is a programming-language capability that lets a common interface or operation work with values of different types while allowing behavior to vary by type or implementation.
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