Copy trait
Copy is a Rust marker trait indicating that values of a type can be duplicated implicitly rather than moved.
Learn Rust in a Month of Lunches
A copy type is a Rust type whose values can be duplicated implicitly by copying their bits rather than transferring ownership.
- How it is used
- Explains why simple values can be passed to functions repeatedly without losing access to the original.
- How deep it goes
- Works through repeated calls, trait documentation, and a moved-value error; stops short of implementing Copy.
- Examples
- Contrasts repeated calls with an i32 against a moved String, then shows cloning and passing a reference.
- What you can do after
- Diagnose/debug with it by recognizing why repeated use works for a Copy value but fails after moving a String.
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Rust in Action: Systems programming concepts and techniques
Copy is a Rust marker trait whose implementation permits values of a type to be implicitly duplicated rather than moved.
- How it is used
- Clarifies why primitive values remain usable after ownership-taking calls while user-defined values ordinarily move.
- How deep it goes
- Explains implicit duplication, contrasts Clone, identifies limitations, and demonstrates deriving or manually implementing the traits.
- Examples
- Uses integers, a CubeSat struct, a status enum, compiler errors, and paired Copy-versus-move listings.
- What you can do after
- Apply Copy by recognizing implicit duplication, diagnosing moved-value errors, and deriving or implementing Copy for suitable types.
Read how Rust in Action: Systems programming concepts and techniques explains Copy trait →
Refactoring to Rust
The Copy trait marks Rust types whose values can be duplicated implicitly without moving ownership from the original binding.
- How it is used
- Explains why passing a value to a function can make the original binding unavailable on a later use.
- How deep it goes
- Defines Copy through a concrete compiler error but stops short of implementation rules or trait derivation.
- Examples
- Uses an art museum program, an Artwork struct containing String, two function calls, and the resulting E0382 diagnostic.
- What you can do after
- Evaluate why a repeated value use fails after a function call that moves ownership.
Related concepts
- copycontrasts with · Copying is the creation of a separate representation of an existing value, object, or data, preserving some or all of its contents or state.
- primitive data typeimplemented by · A primitive data type is a fundamental, language-provided type for representing a basic value, rather than a composite of multiple values.
- stringcontrasts with · A string is a programming-language value representing an ordered sequence of characters or character units as text.
- copy semanticsuses · Copy semantics are the rules by which copying a value creates an independent representation while leaving the original usable.
- destructorcontrasts with · A destructor is an operation associated with an object or value that performs cleanup when its lifetime ends.
- traitkind of · A trait is a type-level construct that defines reusable behavior or members that types can implement or compose.
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