The very related concept of design by contract, pioneered in Eiffel by Bertrand Meyer, is something I've found absolutely essential for writing robust code. Eve

The very related concept of design by contract, pioneered in Eiffel by Bertrand Meyer, is something I've found absolutely essential for writing robust code. Every programmer should be taught to reason about preconditions, postconditions, and logical invariants, and properly document those when writing interfaces. Not bothering to think about edge cases is a major reason for software fragility.