m03-mutability

Rust borrow checker errors E0499 and E0502 often require interior mutability to resolve. A decision framework maps borrow patterns to concrete primitives, guiding safe mutation strategies to prevent borrow conflicts and runtime panics.

Interior mutability with Cell vs RefCell depends on Copy semantics. Cell is suitable for Copy types, while RefCell handles complex types by enforcing borrow rules at runtime to prevent mutation panics in single-threaded contexts.

Mutex and RwLock provide thread-safe mutability in Rust. Mutex offers exclusive access for multi-threaded writes, while RwLock allows multiple concurrent readers, selecting the correct primitive based on thread context prevents concurrency issues.

The best way to apply interior mutability in Rust is a decision framework mapping ownership models to primitives. This strategy keeps code maintainable and thread-safe by providing concrete design patterns for safe data mutation.

Rust RefCell panics during multiple borrows because interior mutability rules are enforced at runtime. Guardrails for correct usage prevent these panics by ensuring safe borrow patterns and preventing conflicting mutable accesses.

Interior mutability is often needed for single-threaded Rust modules when borrow checker errors block safe mutation. Primitives like Cell and RefCell allow internal mutation while preserving external immutability to resolve borrow conflicts.