macro_rules! Rust provides a powerful macro system that allows metaprogramming. As you've seen in previous chapters, macros look like functions, except that their name ends with a bang …

This chapter will introduce Rust’s declarative Macro-By-Example system by explaining the system as a whole. It will do so by first going into the construct’s syntax and its key parts and then …

When a macro is invoked, the macro_rules! interpreter goes through the rules one by one, in lexical order. For each rule, it tries to match the contents of the input token tree against that …

Roughly orthogonally to the two macro implementation methods, there are (broadly) three macro namespaces, with different invocation syntaxes: "function-like": Invoked as macro!(...) (where …

Dec 19, 2025 · A: Start with macro_rules! for pattern-based substitution. Graduate to a procedural macro when you need the full power of Rust's syntax trees and compiler introspection for …

Nov 29, 2024 · This guide explores the syntax, examples, and detailed explanation of macro_rules! in Rust, helping you leverage its potential for cleaner and more efficient code.

However, unlike macros in C and other languages, Rust macros are expanded into abstract syntax trees, rather than string preprocessing, so you don't get unexpected precedence bugs. …

Dec 30, 2023 · Macros can take input parameters and generate code based on those parameters. The parameters are specified within the macro definition and can be used in the generated …

Jan 2, 2025 · Macros in Rust are a way to define rules that are expanded at compile time. Unlike functions, macros work with tokens, allowing developers to perform meta-programming by …

macro_rules allows users to define syntax extension in a declarative way. We call such extensions “macros by example” or simply “macros”. Each macro by example has a name, …