Procedural macro
A procedural macro is a Rust macro implemented as a program that transforms an input token stream into generated code during compilation.
Write Powerful Rust Macros
A procedural macro is a Rust macro implemented as code that receives a token stream and programmatically produces another token stream.
- How it is used
- Generates compiler-checked Rust code when declarative macros cannot express required transformations.
- How deep it goes
- Explains TokenStream input and output, lexing, parsing, setup, testing, and expansion inspection without claiming full compiler internals.
- Examples
- Builds a Hello derive macro that adds behavior to struct Example through a macro library and consumer application.
- What you can do after
- Build it from scratch as a derive-macro library, test generated code, and inspect expansions with cargo expand.
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Idiomatic Rust
A procedural macro is a Rust macro implemented as code that programmatically transforms a token stream into generated Rust code.
- How it is used
- Generates Rust code at compile time for language extensions and repetitive implementations, particularly derives.
- How deep it goes
- Works through raw token output and a derive implementation with parsed input and generics, but limits treatment to basics.
- Examples
- Demonstrates a greeting macro and a PrintName derive alongside its generated trait implementation.
- What you can do after
- Build a basic function-like macro or derive macro in a procedural-macro library crate.
Related concepts
- attribute macroincludes · An attribute macro is a compile-time procedural transformation attached to a language item that generates replacement or additional code.
- derive macroincludes · A Rust derive macro is an attribute that automatically generates implementations of specified traits or related functionality for a type.
- function-like macroincludes · A function-like macro is a macro invoked with function-like syntax that accepts token input and expands or transforms it into generated source.
- TokenStreamuses · TokenStream is a sequence of Rust source tokens used as input or output during procedural macro expansion and code generation.
- macrokind of · A macro is a named construct that expands or transforms source code, commands, or templates before or during execution.
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