Macro parameter
A macro parameter is a named placeholder in a macro definition that receives the corresponding argument from a macro invocation for expansion.
Write Powerful Rust Macros
A macro variable is a named binding in a declarative macro that refers to syntax captured by a matcher.
- How it is used
- Uses named bindings to pass matched Rust syntax from a declarative macro matcher into its transcriber.
- How deep it goes
- Defines dollar-prefixed bindings and fragment specifiers, then compares precise matches with broad `tt` matching.
- Examples
- Demonstrates empty-vector expansion, expression capture, vector insertion, and repeated comma-separated expressions.
- What you can do after
- Build declarative macro arms that capture expressions and expand them into generated Rust code.
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Modern C
A macro parameter is a named placeholder in a function-like macro definition that receives replacement tokens from a macro invocation.
- How it is used
- Supports reusable textual transformations in C function-like macros during the preprocessing stage.
- How deep it goes
- Explains naming, argument parsing, recursive expansion, substitution, and stringification, but stops short of broader macro operators.
- Examples
- Uses BYTECOPY substitutions and trace macros that stringify expressions such as sum and sum*argc.
- What you can do after
- Apply it via C preprocessing to predict parameter substitution and preserve or stringify invocation arguments deliberately.
Related concepts
- macroused by · A macro is a named construct that expands or transforms source code, commands, or templates before or during execution.
- stringification operatorused by · The stringification operator is the C preprocessor operator # that converts a macro argument's textual spelling into a string literal.
- inputcontrasts with · An input is a value, information, or signal supplied to a system, computation, or interface for processing or to influence its behavior.
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