Macros

References

• Little Book of Macros

• Rust macros are good since they generally:

  • avoid unintended side-effects
  • do not result in bizarre error messages
  • are not simple text substitutions, they must be parseable
  • are subject to much more rigorous analysis during compilation
  • are an elegant way to add a lot of power to a program, with limited risk
  • are well thought out and tightly integrated into the ecosystem
  • have few detractors within the Rust community
  • can only expand to what is expected at that position (e.g. expression or type definition)
  • can never expand to an incomplete or invalid construct (e.g. unbalanced parenthesis). In C you could #define Foo Bar( that is impossible in Rust.
  • can be recursive (up to 32 levels by default)
  • are actually a big selling point of the language