How to write easy to refactor Rust

Note: this section is still under development, who knows if it’ll exist in the future

Tags: rust , easy-to-refactor

Ideas

• Type inference is your friend
  • Try and write types for something once. The more you write types for something the more you’d have to change it.
    • Use Self for the return type of constructors with ..Default::default()
    • Associated types can be used so you don’t have to keep writing the type
    • Rust supports -> impl Something, you don’t have to write out the concrete type every time
    • Try and implement as many built in traits or traits as possible
    • Don’t be afraid to implement your trait for built in types
  • Instead of casting all the time, let the compiler infer the cast
• impl blocks make things really hard, try creating traits to abstract away all that pain
  • Traits allow you to define the relationship between different types that you’re using, plus adding a little bit of logic. There is a limit to their power though (doesn’t work when you want to construct a particular struct)
    • reference
• infer types more
  • only works for stack allocated variables (not params)
• use free generic variables when you don’t care
• Know when to use generic parameters or associated types
• Write more functional code
  • FP is the best at composable / refactorable code
  • This is also useful when writing tests, you know the core pillars that it’s built on are working fine, so it’s easier to adapt the tests
• Avoid having to refactor at all
  • Try TDD - write the API usage before writing the API, you might find that what you were thinking doesn’t work with the borrow checker
    • A bit of info here
    • Also here
  • Try and think of three other possible usages of the API that you’ve written, try to sympathise with their use cases
• Pass on the benefits
  • You should be writing APIs that help people write code that’s easy to refactor. This means implementing Default or Vector methods, if you can work with iterating over a value you should implement iter / from iter methods.
  • Find crates that could possibly make use of your library and implement traits for them. These could be hidden behind a feature flag.
• Generics generate more code so be careful
• Macros for repretetive tasks
  • mdbook get and insert macro
    • This case is an example of using a macro to allow try_into and into to work properly
  • Quick tip: use the paste libray to make code generation even better
  • Rule of thumb: if you have to write something multiple times why not write it once with a macro?
• If all else fails, learn some Vim-fu