Frogs design

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Latest revision as of 04:31, 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.

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 '''An OO model of frogs.''' This beautiful design appeared in the 2004 427 exam.
-[[image:frogs.gif|900px]]
+[[image:frogs.gif]]
 == Design notes ==
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 * ''Toad''s eat ''AdultFrogs''.
-== Broken heuristics ==
+== Criticisms ==
-* [[Avoid becomes]] - ''Frog'' phases of life are modeled by inheritance: ''Egg'' ''Tadpole'', ''AdultFrog''.
+* [[2009 frog design criticisms]]
-* [[Beware type switches]] - the ''phase'' variable in ''Frog'' is based on the type of an object (''Frog'').
-* [[Beware value switches]] - the ''swim()'' method in ''Tadpole'' differs in behavior based on the value of an attribute (''type'').
-* [[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.
-== "Feels Bad" ==
+* [[2010 frog design criticisms]]
-* ''Toad'' is a subclass of ''AdultFrog''.
-* ''FrogBrain'' contains an array of ''Egg''.
-:''Why do these things feel bad? --[[User:Warwick Irwin|Wal]]''
-== Go export yourself ==
-Should a ''Frog'' be able to export itself?
-[[image:frog.jpg]]