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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Maintainable code - some positive advice

Don't ask what class an object belongs to
Don't enquire where your cursor is
Don't do two things in a call
Don't duplicate data or code
Don't put two or more values in the same cell

There's lots of different ways of coding - from "dog's dinner" to "Picasso". The dog's dinner looks a mess and is very quickly gone and forgotten (even by the dog, who wants more), but a Picasso is a piece of beauty and lasts for generations. We can all feed the dog, but very few of us are Picassos. What we can all do is to make a good job of decorating a room so that it lasts and looks fresh for a year or two, and functions well without redecoration for pehaps 5 or 10 years.

The first time you slapped paint on, as a child, it wasn't going to last for even a year, was it? But with practise and applying a bit of discipline to yourself, you can do rather better now? Thought so! And it's very much the same with coding; your first program on a Perl course or your first MySQL database will be written to test basic functionallity - to check that you CAN store that data / stick that paint roughly where you want it on the wall. Improvements come once you understand the mechanism and have tested it.

Here are some of the improvements that you can make between "first test" and real application:

Don't ask what class an object belongs to. Use polymorphism, so that no matter what type of object you run a method on, your code will automatically do the right thing. If you redefine what an operator or method does (oveloading) by defining two blocks of code with the same name and footprint, then your need for lots of switches or if, elif, elif, elif sequences is eliminated.

Don't enquire where your cursor is, or what status your application is in - remember it in your code. Any piece of code that goes out to discover where it stands / what step it's at gets complex and hard to maintain - and such enquiries are prone to error. Much better to remember - it's often as simple as having a single integer status variable.

Don't do two things in a call. You want to format a piece of data and print it out? Sure - write a piece of code to do it and it'll work well. Until, one day, you want to format the data and do something else with it. Put it up on a widget or burn it into a graphic, perhaps. And the piece of code that's called from all over your program to do "a" and "b" suddenly doesn't seem so clever as this time you only wasnt "a". Much better to write code that performs a single logical operation in a single call; you can always write a wrapper to bring two commonly used operations together if you need to do that frequently.

Don't duplicate data or code. If you find yourself cutting and pasting code - WRONG. You're creating a branch which will give you two threads to debug, maintain for the life of the code. Better to take the code that's going to be used several times over, give it a name (i.e. make it a function, sub, def, proc) and call it by name. "But I need to change some things in the copy" you say. Yes indeed - those things you need to change are helping you to identify which elements are your parameters.

Don't put two or more values in the same cell. As soon as you start putting comma separated list, multiple space separated names or whatever in a string or database cell, you have an issue with the commands or code that searches them. One value per simple variable, one value per cell please. In programming terms, you can use lists, tuples, dictionaries (Python), arrays and lists (Tcl), hashes and lists (Perl) and arrays or any one of the many utility classes (Java). In database terms, you're looking at an additional table and a join. The decign may get more complex, but the data is kept simpler and unique. Find a data error and you've just one correction, not a multitude!

Why not review your coding against the suggestions I've made above? Get into the habit of following the guidelines suggested. And you'll find that you naturally move from producing a very temporary solution to an issue to something that will, far better, stand the test of time.
(written 2007-01-21, updated 2007-05-18)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
W512 - Web and Intranet - Site Design Aspects
  [229] A fortunate accident - (2005-02-27)
  [261] Putting a form online - (2005-03-29)
  [288] Colour blindness for web developers - (2005-04-22)
  [319] Accommodation and landing pages - (2005-05-21)
  [345] Spotting a denial of service attack - (2005-06-12)
  [352] Improved mining techniques! - (2005-06-19)
  [391] One mans pleasure is another mans poison - (2005-07-26)
  [510] Dynamic Web presence - next generation web site - (2005-11-29)
  [556] Colour doesn't have to mean colourful - (2006-01-06)
  [649] Denial of Service ''attack'' - (2006-03-17)
  [718] Protecting images from theft - (2006-05-12)
  [795] Remember a site's non-technical issues too - (2006-07-07)
  [823] An excellent use for a visitor count? - (2006-08-05)
  [859] Put the answer in context - it may be printed - (2006-09-08)
  [918] Databases needn't be frightening, hard or expensive - (2006-11-08)
  [1015] Search engine placement - long term strategy and success - (2006-12-30)
  [1054] UK legal requirements for your commercial web site - (2007-01-27)
  [1353] Mood shots - (2007-09-16)
  [1598] Every link has two ends - fixing 404s at the recipient - (2008-04-02)
  [2214] Global Index to help you find resources - (2009-06-01)
  [3517] Tags used in writing this blog - (2011-11-12)
  [3563] How big is a web page these days? Does the size of your pages matter? - (2011-12-26)
  [3589] Promoting a single one of your domains on the search engines - (2012-01-22)

Q907 - Object Orientation and General technical topics - Object Orientation: Design Techniques
  [80] OO - real benefits - (2004-10-09)
  [236] Tapping in on resources - (2005-03-05)
  [507] Introduction to Object Oriented Programming - (2005-11-27)
  [534] Design - one name, one action - (2005-12-19)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [747] The Fag Packet Design Methodology - (2006-06-06)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [836] Build on what you already have with OO - (2006-08-17)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1224] Object Relation Mapping (ORM) - (2007-06-09)
  [1435] Object Oriented Programming in Perl - Course - (2007-11-18)
  [1528] Object Oriented Tcl - (2008-02-02)
  [1538] Teaching Object Oriented Java with Students and Ice Cream - (2008-02-12)
  [2169] When should I use OO techniques? - (2009-05-11)
  [2170] Designing a heirarcy of classes - getting inheritance right - (2009-05-11)
  [2327] Planning! - (2009-08-08)
  [2380] Object Oriented programming - a practical design example - (2009-08-27)
  [2501] Simples - (2009-11-12)
  [2523] Plan your application before you start - (2009-12-02)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2741] What is a factory? - (2010-04-26)
  [2747] Containment, Associative Objects, Inheritance, packages and modules - (2010-04-30)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2865] Relationships between Java classes - inheritance, packaging and others - (2010-07-10)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2953] Turning an exercise into the real thing with extreme programming - (2010-09-11)
  [2977] What is a factory method and why use one? - Example in Ruby - (2010-09-30)
  [3063] Comments in and on Perl - a case for extreme OO programming - (2010-11-21)
  [3085] Object Oriented Programming for Structured Programmers - conversion training - (2010-12-14)
  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
  [3454] Your PHP website - how to factor and refactor to reduce growing pains - (2011-09-24)
  [3607] Designing your application - using UML techniques - (2012-02-11)
  [3760] Why you should use objects even for short data manipulation programs in Ruby - (2012-06-10)
  [3763] Spike solutions and refactoring - a Python example - (2012-06-13)
  [3798] When you should use Object Orientation even in a short program - Python example - (2012-07-06)
  [3844] Rooms ready for guests - each time, every time, thanks to good system design - (2012-08-20)
  [3878] From Structured to Object Oriented Programming. - (2012-10-02)
  [3887] Inheritance, Composition and Associated objects - when to use which - Python example - (2012-10-10)
  [3928] Storing your intermediate data - what format should you you choose? - (2012-11-20)
  [3978] Teaching OO - how to avoid lots of window switching early on - (2013-01-17)
  [4098] Using object orientation for non-physical objects - (2013-05-22)
  [4374] Test driven development, and class design, from first principles (using C++) - (2014-12-30)
  [4430] The spirit of Java - delegating to classes - (2015-02-18)
  [4449] Spike solution, refactoring into encapsulated object methods - good design practise - (2015-03-05)
  [4628] Associative objects - one object within another. - (2016-01-20)

P711 - An Introduction to Standards in Perl
  [242] Satisfaction of training - (2005-03-11)
  [668] Python - block insets help with documentation - (2006-04-04)
  [743] How to debug a Perl program - (2006-06-04)
  [945] Code quality counts - (2006-11-26)
  [965] KISS - one action per statement please - Perl - (2006-12-05)
  [1221] Bathtubs and pecking birds - (2007-06-07)
  [1345] Perl and Shell coding standards / costs of an IT project - (2007-09-11)
  [1395] Dont just convert to Perl - re-engineer! - (2007-10-18)
  [1555] Advanced Python, Perl, PHP and Tcl training courses / classes - (2008-02-25)
  [1728] A short Perl example - (2008-07-30)
  [1853] Well structured coding in Perl - (2008-10-24)
  [1863] About dieing and exiting in Perl - (2008-11-01)
  [2375] Designing your data structures for a robust Perl application - (2009-08-25)
  [2688] Security considerations in programming - what do we teach? - (2010-03-22)
  [2875] A long day in Melksham ... - (2010-07-17)
  [3398] Perl - making best use of the flexibility, but also using good coding standards - (2011-08-19)
  [4326] Learning to program - comments, documentation and test code - (2014-11-22)

H115 - Designing PHP-Based Solutions: Best Practice
  [123] Short underground journeys and a PHP book - (2004-11-19)
  [237] Crossfertilisation, PHP to Python - (2005-03-06)
  [340] Code and code maintainance efficiency - (2005-06-08)
  [394] A year on - should we offer certified PHP courses - (2005-07-28)
  [426] Robust checking of data entered by users - (2005-08-27)
  [563] Merging pictures using PHP and GD - (2006-01-13)
  [572] Giving the researcher power over database analysis - (2006-01-22)
  [839] Reporting on the 10 largest files or 10 top scores - (2006-08-20)
  [896] PHP - good coding practise and sticky radio buttons - (2006-10-17)
  [936] Global, Superglobal, Session variables - scope and persistance in PHP - (2006-11-21)
  [1052] Learning to write secure, maintainable PHP - (2007-01-25)
  [1166] Back button - ensuring order are not submitted twice (PHP) - (2007-04-28)
  [1181] Good Programming practise - where to initialise variables - (2007-05-09)
  [1182] Painting a masterpiece in PHP - (2007-05-10)
  [1194] Drawing hands on a clock face - PHP - (2007-05-19)
  [1321] Resetting session based tests in PHP - (2007-08-26)
  [1323] Easy handling of errors in PHP - (2007-08-27)
  [1381] Using a MySQL database to control mod_rewrite via PHP - (2007-10-06)
  [1389] Controlling and labelling Google maps via PHP - (2007-10-13)
  [1390] Converting from postal address to latitude / longitude - (2007-10-13)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1482] A story about benchmarking PHP - (2007-12-23)
  [1487] Efficient PHP applications - framework and example - (2007-12-28)
  [1490] Software to record day to day events and keep an action list - (2007-12-31)
  [1533] Short and sweet and sticky - PHP form input - (2008-02-06)
  [1623] PHP Techniques - a workshop - (2008-04-26)
  [1694] Defensive coding techniques in PHP? - (2008-07-02)
  [1794] Refactoring - a PHP demo becomes a production page - (2008-09-12)
  [2199] Improving the structure of your early PHP programs - (2009-05-25)
  [2221] Adding a newsfeed for your users to a multipage PHP application - (2009-06-06)
  [2430] Not just a PHP program - a good web application - (2009-09-29)
  [2679] How to build a test harness into your PHP - (2010-03-16)
  [3539] Separating program and artwork in PHP - easier maintainance, and better for the user - (2011-12-05)
  [3813] Injection Attacks - PHP, SQL, HTML, Javascript - and how to neutralise them - (2012-07-22)
  [3820] PHP sessions - a best practice teaching example - (2012-07-27)
  [3926] Filtering PHP form inputs - three ways, but which should you use? - (2012-11-18)
  [4069] Even early on, separate out your program from your HTML! - (2013-04-25)
  [4118] We not only teach PHP and Python - we teach good PHP and Python Practice! - (2013-06-18)
  [4641] Using an MVC structure - even without a formal framework - (2016-02-07)
  [4691] Real life PHP application using our course training MVC example - (2016-06-05)


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Maintainable code - some positive advice
Bounce, bounce, bounce
Bang! Train campaign hits home
Call for appropriate train services - Swindon, Bristol, Bath, West Wilts, Severn Beach etc
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Nested exceptions in Python
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