Frogs design

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Revision as of 02:31, 15 July 2010

An OO model of frogs. This beautiful design appeared in the 2004 427 exam.

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.

@@ Line 12: / Line 12: @@
 * ''Toad''s eat ''AdultFrogs''.
-== Broken heuristics ==
+== Criticisms ==
-* [[Riel's heuristics]]
+* [[2009 frog design criticisms]]
-** 2.1 [[Hide data within its class]]: The ''AdultFrog'' class exposes an array of eggs it has laid.
-** 2.9 [[Keep related data and behavior in one place]]: ''Frog'' and ''FrogBrain'' are separate classes.
-** 3.5 [[Interface should be dependent on model]]: The ''Move'' interface contains a method called ''display''; the model is dependent on the interface
-** 3.9 [[Avoid verb classes]]: The ''Move'' interface is a verb. It could be called ''Movable'' or similar (although that name is still not great for other reasons).
-** 3.10 [[Agent classes irrelevant]]: The ''Biologist'' class is an agent.
-** 5.14 [[Avoid becomes]]: A frog will at various stages be an egg, tadpole and adult frog.
-*** Solution: State or strategy pattern
-** 5.1 [[Inheritance for specialization]]: A toad is not a frog; it's [[Avoid_inheritance_for_implementation|inheritance for implementation]].
-** 5.17 [[Avoid no-op overrides]]: The ''hop'' and ''swim'' methods of ''Egg'' do nothing.
-** 5.12 [[Beware type switches]]: ''Tadpole'' has a type attribute which is used in ''swim()'' (5.13 broken as well?)
-* The biologist should have the saute method, not the frog itself.
-* For a better solution to the XML export ability, see [[a froggy visitor]] (last year's class)