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A mutable square is not a mutable rectangle, because a mutablr rectangle can change its width independently of its length. This is the classic problem of contra
by tamana 11y ago
A mutable square is not a mutable rectangle, because a mutablr rectangle can change its width independently of its length. This is the classic problem of contravariance: subtyping in the face of mutability.
- Bluestrike2 11y agoGood point. Without giving it much if any thought, I made an assumption--that the square is immutable--that probably wouldn't even be accurate in this context. In fact, it's the usual example used to talk about substitutability. Oops.