Frogs design
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Revision as of 22:58, 22 July 2008 by Yugan Yugaraja (Talk | contribs)
An OO model of frogs. This beautiful design appeared in the 2004 427 exam.
Design notes
- This design models the lifecycles of Frogs.
- A Frog begins life as an Egg, grows into a Tadpole and then an AdultFrog.
- A FrogBrain belongs to a Frog and manages its behaviour.
- There is one Biologist, Igor, who sometimes moves Frogs around. Igor has been known to fry their legs in white wine.
- Toads don’t have the same lifecycle as Frogs, but they look and act a lot like Frogs.
- Toads eat AdultFrogs.
Design Critique
This design is perfect. It cannot be faulted.
Broken heuristics
- Beware type switches - Frog phases: Egg, Tadpole, AdultFrog.
- Beware value switches - Tadpole
- Avoid no-op overrides ("Design by Contract") - the derived class Egg overrides the base class's hop() and swim() methods with methods which does nothing.
- One key abstraction - the Move interface contains more than one key abstraction. It contains methods to move such as hop() and swim(), but it also contains a display() method which is a separate key abstraction.
- This is a good start, but needs some explanation of how the rules are broken here. Also needs a note about this conribution on the talk page. --Wal 22:44, 22 July 2008 (UTC)
