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The Light bulb moment when people see how Object Orientation works in real use
A big "light bulb" moment for many customers is when they "get" object inheritance. And one of the best ways of explaining it is by writing an example. On Wednesday, I wrote an example during our Python Course - taking a customer of Well House Consultants as my base class, then defining two extended classes (i.e. subtypes with extra and amended features) called "resident" and "delegate". See [source]. In my example, all customers have names and a length of stay, but the price algorithm differs in the subclasses. I've also redefined the "+" operator, so that if I add two residents together they end up sharing a room, and if I add a number to a resident, that extends their stay by that number of nights. When I call up the name of a customer, it runs the same code for any customer, but when I call up the price for a customer, it runs different code depending on whether it's a delegate or a resident. This is "Polymorphism" Python is very neat in that I can define all of the classes in a single file (A Java example would have had three or 4 files of source), and it's much cleaner than objects in Perl. Which is why Python is such a superb language for researchers. (written 2010-05-28) Associated topics are indexed under Q907 - Object Orientation and General technical topics - Object Orientation: Design Techniques[3978] Teaching OO - how to avoid lots of window switching early on - (2013-01-17) [3928] Storing your intermediate data - what format should you you choose? - (2012-11-20) [3887] Inheritance, Composition and Associated objects - when to use which - Python example - (2012-10-10) [3878] From Structured to Object Oriented Programming. - (2012-10-02) [3844] Rooms ready for guests - each time, every time, thanks to good system design - (2012-08-20) [3798] When you should use Object Orientation even in a short program - Python example - (2012-07-06) [3763] Spike solutions and refactoring - a Python example - (2012-06-13) [3760] Why you should use objects even for short data manipulation programs in Ruby - (2012-06-10) [3607] Designing your application - using UML techniques - (2012-02-11) [3454] Your PHP website - how to factor and refactor to reduce growing pains - (2011-09-24) [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23) [3085] Object Oriented Programming for Structured Programmers - conversion training - (2010-12-14) [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) [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) [236] Tapping in on resources - (2005-03-05) [80] OO - real benefits - (2004-10-09) Y112 - Python - Objects - Intermediate [4094] Python Properties - how and why - (2013-05-18) [4028] Really Simple Class and Inheritance example in Python - (2013-03-04) [3796] Backquote, backtic, str and repr in Python - conversion object to string - (2012-07-05) [3524] Metaclasses (Python) and Metatables (Lua) - (2011-11-17) [3472] Static variables in functions - and better ways using objects - (2011-10-10) [3442] A demonstration of how many Python facilities work together - (2011-09-16) [3002] A list of special method and attribute names in Python - (2010-10-17) [2994] Python - some common questions answered in code examples - (2010-10-10) [2905] Defining static methods in Python - (2010-08-05) [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14) [2722] Mixins example in Python - (2010-04-14) [2720] Multiple inheritance in Python - complete working example - (2010-04-14) [2693] Methods that run on classes (static methods) in Python - (2010-03-25) [2485] How do I set up a constant in Python? - (2009-10-31) [2409] TypeError: super() argument 1 must be type, not classobj (Python) - (2009-09-18) [2368] Python - fresh examples of all the fundamentals - (2009-08-20) [1819] Calling base class constructors - (2008-10-03) [1661] Equality, sameness and identity - Python - (2008-05-31) [1644] Using a utility method to construct objects of different types - Python - (2008-05-17) [1517] Python - formatting objects - (2008-01-24) [1146] __new__ v __init__ - python constructor alternatives? - (2007-04-14) [964] Practical polymorphism in action - (2006-12-04) [903] Pieces of Python - (2006-10-23) [477] Class, static and unbound variables - (2005-10-25) [383] Overloading of operators on standard objects in Python - (2005-07-19) [296] Using a Python dictionary as a holder of object attributes - (2005-04-30) 5450
Some other Articles
Melksham to London (Heathrow, and Central London)Cost of Sales Sleeping in on Sunday Factory methods and SqLite in use in a Python teaching example The Light bulb moment when people see how Object Orientation works in real use Course Lunches The Perl Survey Tell the Melksham Chamber or you only have yourself to blame The 500 pound question to get you started Formatted Printing in Python |
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Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82 at 50 posts per pageThis is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.
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