Rust Design Patterns

Start from the compiler error, API decision, or code under review. Read only the reference sections that match; the catalog is not a checklist to apply everywhere.

Establish applicability

• Check the crate's edition, MSRV, and whether it is a library or binary. Library crates carry compatibility constraints (non_exhaustive, lint policy, public types) that binaries do not.
• Follow the crate's existing conventions for errors, builders, and unsafe boundaries before introducing a new pattern.
• For borrow checker errors, reshape ownership before reaching for clone, Rc, or Arc. Treat a clone as a deliberate cost, not a way to silence the compiler.
• When a lifetime is too short and no borrow reshaping fits, prefer an owned type over widening lifetimes or adding 'static bounds.

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