Rustlings macros2: What order you write macro definitions in matters
InstructorChris Biscardi
Published 4 years ago
Updated 3 years ago
README for this exercise.
Chris Biscardi: [0:00] Macros2 has a very similar setup to macros1, where we have a main function with a body that calls our macro and a macro_rules definition that defines my_macro with a println. The help message from the Rust compiler asks us if we've added the macro_use on the module import. It warns us because we have the unused macros warning turned on, which is on by default.
[0:19] However, macros need to be defined before they're used. If we switch the order of the main function body and the macro, our test work. This ordering for macros needing to be defined before they're used is different than most other things in Rust.
egghead
~ 16 minutes ago
Markdown supported.
Become a member to join the discussionEnroll Today
Member comments are a way for members to communicate, interact, and ask questions about a lesson.
The instructor or someone from the community might respond to your question Here are a few basic guidelines to commenting on egghead.io
Be on-Topic
Comments are for discussing a lesson. If you're having a general issue with the website functionality, please contact us at support@egghead.io.
Avoid meta-discussion
Code Problems?
Should be accompanied by code! Codesandbox or Stackblitz provide a way to share code and discuss it in context
Details and Context
Vague question? Vague answer. Any details and context you can provide will lure more interesting answers!