Identifier fragment specifier
An identifier fragment specifier is Rust declarative macro syntax that matches an identifier token, such as a variable or function name.
Learn Rust in a Month of Lunches
An identifier fragment specifier matches a Rust identifier such as a variable or function name as macro input.
- How it is used
- Uses ident in macro_rules! patterns to capture names for generated Rust code.
- How deep it goes
- Defines ident through focused macro examples but defers the complete fragment-specifier details.
- Examples
- Demonstrates identifier matching with x, my_vec, print_it, and say_its_nice.
- What you can do after
- Apply it via macro_rules! to capture variable or function names and reuse them in generated code.
Read how Learn Rust in a Month of Lunches explains identifier fragment specifier →
Write Powerful Rust Macros
An identifier fragment specifier matches an identifier token as an input fragment in a Rust declarative macro.
- How it is used
- Reduces repeated implementation code when declarative macros generate methods for named structs and newtypes.
- How deep it goes
- Explains identifier-token matching through a working macro and contrasts it with adding a `ty` fragment for return types.
- Examples
- Uses `FirstName`, `LastName`, `Age`, and `Pay` with a generated `get_value` method.
- What you can do after
- Build declarative macros that accept struct or type names and emit implementations using those captured identifiers.
Read how Write Powerful Rust Macros explains identifier fragment specifier →
Related concepts
- identifieruses · An identifier is a name or value that denotes or distinguishes an entity or program element within a system.
- type fragment specifiercontrasts with · A type fragment specifier is a declarative-macro matcher specifier that matches Rust type syntax.
- expression fragment specifiercontrasts with · An expression fragment specifier is a Rust declarative-macro matcher annotation that matches syntax representing an expression.
- fragment specifierkind of · A fragment specifier is a declarative-macro matcher annotation that specifies the syntactic category of tokens a metavariable can match.
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