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''.
-== Design Critique ==
+== Criticisms ==
-This design is perfect.  It cannot be faulted.
+* [[2009 frog design criticisms]]
-== Broken heuristics ==
+* [[2010 frog design criticisms]]
-* [[Beware type switches]] - ''Frog'' phases: ''Egg'', ''Tadpole'', ''AdultFrog''.
-* [[Avoid "becomes"]] - ''Frog'' phases of life are modeled by inheritance: ''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 more explanation of how the rules are broken here.  Also needs a note about this contribution on the discussion page. --[[User:Warwick Irwin|Wal]]''
-== "Feels Bad" ==
-* ''Toad'' is a subclass of ''AdultFrog''.
-* ''FrogBrain'' contains an array of ''Egg''
-:''Why do these things feel bad? --[[User:Warwick Irwin|Wal]]''