A code smell is a hint that a program's design has a problem, distinct from a bug because the code may still function correctly while being hard to maintain or extend. This concept belongs to software design / code quality in object-oriented programming, and is grounded in principles such as type safety, cohesion, coupling, single responsibility, and explicit error handling. Recognizing smells (overly broad primitive types standing in for a fixed set of values, duplicated logic, unused language features, vague naming, runtime type-checking via `isinstance`, boolean-flag parameters that overload a function's responsibility, silently swallowed exceptions, and generic built-in exceptions used for domain-specific errors) guides refactoring toward designs with higher cohesion and lower coupling.
A code smell is a hint that a program's design has a problem, distinct from a bug because the code may still function correctly while being hard to maintain or extend. This concept belongs to softwar…