When it comes to producing new examples for a course, where better to look than close to home? Yesterday, I was looking for an example to use when I was covering object design in Python and I hit upon working with taps and the water suppy to them.

Looking around, we have quite a few taps here; several of them are in the training centre part of the building (the first two that I've pictured) and others are elsewhere.

The taps differ a little - some are mixer taps, others (such as the outside tap) are cold only,and the tap in the kitchen is a spectacular tap that I've christened to be a "supertap". Together, these make a great example of a base class and the ability to define inheritance.

Our sample application went further. We defined connection objects which describe which mains supply each tap is connected to in the building, and we then define a maximum flow through that connection. This allows our python application to know when there isn't enough capacity available when someone tries to turn a tap on.


If you're writing code in an object oriented language such as Python, it's important that you think carefully about the objects that you're dealing with and specify the classes and methods that you'll be using as carefully as possible at the start. On many of our courses, we include modules on object oriented design in order to help you save time in the long term by getting tings right from the start.

It's only when you start working with classes in this way that you realise just what a powerful resource they are ...

(written 2005-03-05, updated 2006-06-05)

 Q907 - Object Orientation and General technical topics - Object Orientation: Design Techniques
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  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
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  [3063] Comments in and on Perl - a case for extreme OO programming - (2010-11-21)
  [2977] What is a factory method and why use one? - Example in Ruby - (2010-09-30)
  [2953] Turning an exercise into the real thing with extreme programming - (2010-09-11)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2865] Relationships between Java classes - inheritance, packaging and others - (2010-07-10)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2747] Containment, Associative Objects, Inheritance, packages and modules - (2010-04-30)
  [2741] What is a factory? - (2010-04-26)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2523] Plan your application before you start - (2009-12-02)
  [2501] Simples - (2009-11-12)
  [2380] Object Oriented programming - a practical design example - (2009-08-27)
  [2327] Planning! - (2009-08-08)
  [2170] Designing a heirarcy of classes - getting inheritance right - (2009-05-11)
  [2169] When should I use OO techniques? - (2009-05-11)
  [1538] Teaching Object Oriented Java with Students and Ice Cream - (2008-02-12)
  [1528] Object Oriented Tcl - (2008-02-02)
  [1435] Object Oriented Programming in Perl - Course - (2007-11-18)
  [1224] Object Relation Mapping (ORM) - (2007-06-09)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1047] Maintainable code - some positive advice - (2007-01-21)
  [836] Build on what you already have with OO - (2006-08-17)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [747] The Fag Packet Design Methodology - (2006-06-06)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [534] Design - one name, one action - (2005-12-19)
  [507] Introduction to Object Oriented Programming - (2005-11-27)
  [80] OO - real benefits - (2004-10-09)

Y301 - Python - Class Interaction - an example
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [964] Practical polymorphism in action - (2006-12-04)

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Conventional restraints removed
What and why for the epoch
Difficulties with a trolley
Crossfertilisation, PHP to Python
Tapping in on resources
Preparation for a day's work
How to get the best from your supplier
Giving customers best value
Diverse activities
Feedback as lifeblood