erg/doc/EN/dev_guide/rust_code_guideline.md

Guidelines for Rust code

local rules

• Use log! for output for debugging (use println! etc. for output processing that is also necessary for release).
• Unused or internal variables/methods (private and used only for specific functions) must be prefixed with _. If you want to avoid conflicts with reserved words, add one _ to the end.

Recommended code

• Define and use domain-specific Enums instead of numeric enumerations or bools.
• Keep access modifiers to a minimum. Prioritize using pub(mod) or pub(crate) even when publishing.
• Convert an iterable object in a for expression explicitly to an iterator (for i in x.iter() instead of for i in x).
• Lazy evaluation. For example, if default is non-literal, use unwrap_or_else instead of unwrap_or.

Code not encouraged

• Make heavy use of return type overloading. Specifically code that uses a lot of non-obvious .into. This is because type inference results can be counter-intuitive. In this case it is recommended to use from instead.
• Make heavy use of Deref. This effectively poses the same problem as inheritance.

Code that makes decisions based on context

• Define unused helper methods.
• Use unwrap and clone a lot. In some cases there is nothing better than doing so.