Frogs design
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== Broken heuristics == | == Broken heuristics == | ||
| − | * [[Beware type switches]] | + | * [[Beware type switches]] - ''Frog'' phases: ''Egg'', ''Tadpole'', ''AdultFrog''. |
| − | * [[Beware value switches]] | + | * [[Beware value switches]] - ''Tadpole'' |
| − | * [[Avoid no-op overrides]] | + | * [[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]] | + | * [[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. --[[User:Warwick Irwin|Wal]] 22:44, 22 July 2008 (UTC)'' | :''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. --[[User:Warwick Irwin|Wal]] 22:44, 22 July 2008 (UTC)'' | ||
Revision as of 22:58, 22 July 2008
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)
