Macro recursion
Macro recursion is macro-expansion behavior in which a macro expands to another invocation of itself.
Write Powerful Rust Macros
Macro recursion is the expansion behavior in which a macro invocation expands to another invocation of the same macro.
- How it is used
- Uses recursive expansion to delegate macro patterns and reduce repeated generated implementations.
- How deep it goes
- Explains recursive expansion through working macro arms and a compile-time failure, but defers unknown-argument recursion to another example.
- Examples
- Demonstrates recursive `generate_get_value!` delegation and a failing `count!` macro that expands indefinitely.
- What you can do after
- Apply it via `macro_rules!` to route simpler invocations into generalized implementations while recognizing expansion-time recursion failures.
Read how Write Powerful Rust Macros explains macro recursion →
Learn Rust in a Month of Lunches
Macro recursion is a macro-expansion technique in which a macro invokes itself to process or handle additional input.
- How it is used
- Uses self-invocation to process or normalize additional macro input before reaching a terminating expansion.
- How deep it goes
- Shows recursive macro arms and a base case, but stops short of explaining the complete expansion process.
- Examples
- Uses my_macro!, write!, format_args!, and todo! to illustrate recursive calls, argument forwarding, and macro inputs.
- What you can do after
- Evaluate macro-recursive behavior by tracing input-matching arms toward the terminating expansion.
Read how Learn Rust in a Month of Lunches explains macro recursion →
Related concepts
- declarative macroused by · macro_rules! is Rust syntax for defining declarative macros by matching input token patterns and expanding matching rules into generated source code.
- macrouses · A macro is a named construct that expands or transforms source code, commands, or templates before or during execution.
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