Assertions, Preconditions, Postconditions and invariants are our allies to avoid invalid objects. Avoiding them leads to errors.
- Contract breaking
- Hard to debug
- Bad cohesion
- Create strong preconditions
- Raise exceptions
- Fail Fast
- Defensive Programming
- Constructors are an excellent first line of defense
- Anemic Objects lack these rules.
- It’s difficult to find missing preconditions, as long with assertions and invariants.
Always be explicit on object integrity.
Turn on production assertions.
Even if it brings performance penalties.
Data and object corruption is harder to find.
Fail fast is a blessing.
Failure is fashionable. Making is much easier than thinking and failures are not stigma, let’s take this idea to our…
Writing a class without its contract would be similar to producing an engineering component (electrical circuit, VLSI (Very Large Scale Integration) chip, bridge, engine…) without a spec. No professional engineer would even consider the idea.
This article is part of the CodeSmell Series.