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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.
Writing the perfect program in Tcl?

I'm going to disappoint you... there's no such thing as the perfect program. But when I'm writing an answer to a class exercise and showing a sample, I have to make sure it's to a high standard - and that means at least:
• Well commented
• Using good variable names
• Avoiding repetition of constants
Ideally, it would also be
• Robust to any incorrect inputs
• Avoids repeating code (no cut and paste!)
• Efficient in operation
But those latter three elements may require elements of coding (such as procedures and regular expressions) that I may not have taught early on.

So why isn't there a single perfect way to write a program? Consider this...
• Who is going to maintain the program? Does it need to be written for a novice maintainer using simpler structures and lots of comments, or for a an experienced Tcl coder who can easily read some of the more sophisticated regular expression syntax?
• There may be a compromise between speed of operation and ease of reading. Which should be selected?
• Should the code be strongly structured to allow code re-use, or should it be tuned to reduce dependencies on other modules and file - for safer distribution
• May you assume that it will only run on recent versions of Tcl and code using newer features, or is there a realistic chance that the code will need to be run on older systems too. Perhaps your version of Postbuilder isn't yet using Tcl version 8.5, for example
• Should I write my code so that it can all be see on a single page / projector screen by my delegates or should I spread it out so that it can be better understood later when it's posted at places like this for the benefit of people who've not been on the course?
I can't give you a [wrong/right] directive, in general term, on any of the above. But what is certainly right is to make our delegates aware of the issues so that they write their own code with a knowledge and maturity that takes such things into consideration - with an objective of writing code efficiently, and code that's easy to use and easy to maintain thereafter.

Want so see what I mean? There's an example of a quite early answer written during class [here], and a later one [here] which has common logic for user input separated out into a more robust common function loaded from [here]. I'm not saying either is "right", but I prefer the second example because it's more forward useful, and I prefer the first example because my delegates can get to see something fairly effective early on.

Examples from the recent public Tcl Course I ran at our training centre in Melksham. The course is a niche one, and we get delegates from far and wide (you are required to be fluent in English to attend - otherwise it's not fair on other delegates. Clearly the course was a hit... may I share a follow-up letter with you:

Dear Graham,

I am already back in Turkey, comfortably and without any problems.

I send this mail to you to thak once againg for your informative training, help on other subjects (like public transport J), friendship and hospitality. I was very lucky to work with you and I thank you very much for everything.

I wish you, your family, Wellho Ltd. and Melksham the best for the following times.

Best Regards,

(written 2013-11-13, updated 2013-11-16)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Q101 - Object Orientation and General technical topics - Programming Principles
  [2001] I have not programmed before, and need to learn - (2009-01-19)
  [2022] Pre and post increment - the ++ operator - (2009-02-03)
  [2228] Where do I start when writing a program? - (2009-06-11)
  [2310] Learning to write high quality code in Lua - (2009-07-30)
  [2327] Planning! - (2009-08-08)
  [2415] Variable names like i and j - why? - (2009-09-22)
  [2510] The music of the stock market - (2009-11-22)
  [2550] Do not copy and paste code - there are much better ways - (2009-12-26)
  [2586] And and Or illustrated by locks - (2010-01-17)
  [2737] Improving your function calls (APIs) - General and PHP - (2010-04-24)
  [2769] Easy - but for whom? - (2010-05-18)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2915] Looking up a value by key - associative arrays / Hashes / Dictionaries - (2010-08-11)
  [2964] An introduction to file handling in programs - buffering, standard in and out, and file handles - (2010-09-21)
  [3026] Coding efficiency - do not repeat yourself! - (2010-11-02)
  [3456] Stepping stones - early coding, and writing re-usable code quickly - (2011-09-24)
  [3542] What order are operations performed in, in a Perl expression? - (2011-12-07)
  [3548] Dark mornings, dog update, and Python and Lua courses before Christmas - (2011-12-10)
  [3551] Some terms used in programming (Biased towards Python) - (2011-12-12)
  [3673] Object oriented or structured - a comparison in Python. Also writing clean regular expressions - (2012-03-26)
  [3878] From Structured to Object Oriented Programming. - (2012-10-02)
  [3928] Storing your intermediate data - what format should you you choose? - (2012-11-20)
  [3954] Lesson 1 in programing - write clean, reuseable and maintainable tidy code - (2012-12-16)
  [4003] Web and console - same principle, same code - Ruby example - (2013-02-14)
  [4061] Seamless, integrated IT - we have a long way to go! - (2013-04-11)
  [4090] Test Driven Development in Python - Customer Comes First - (2013-05-16)
  [4118] We not only teach PHP and Python - we teach good PHP and Python Practice! - (2013-06-18)
  [4153] Rooms available tonight - how to code an algorithm from first principles - (2013-08-19)
  [4325] Learning to program - what are algorithms and design patterns? - (2014-11-22)
  [4611] Hungarian, Camel, Snake and Kebab - variable naming conventions - (2016-01-03)
  [4632] Remember to ask the question before you listen for the answer - (2016-01-26)
  [4645] What are callbacks? Why use them? An example in Python - (2016-02-11)

T050 - Tcl/Tk - Tcl, Tcl/Tk and Expect - General
  [2429] Tcl scripts / processes on a web server via CGI - (2009-09-27)
  [2474] Using Tcl and Expect to automate repetitive jobs - (2009-10-24)
  [2504] Learning to program in ... - (2009-11-15)
  [2681] Tcl - a great engineering language - (2010-03-17)
  [3192] Tcl - Some example of HOW TO in handling data files and formats - (2011-03-04)
  [3286] Should we cover expect and/or Tk on our public Tcl courses? - (2011-05-11)
  [4434] Public training courses - upcoming dates - (2015-02-21)
  [4460] Using Object Oriented Tcl and the Tk toolkit together - real life example - (2015-03-12)
  [4616] Still teaching Tcl in 2016? - (2016-01-06)

Back to
Regular Expression Substitution - Tcl
Previous and next
Horse's mouth home
Forward to
Exception handling in Tcl
Some other Articles
If elif elif elif - multiway selection in Python
Lists in Tcl - fundamentals in a commented source code example
Tcl + Tk (Wish) - an introduction and revision example
Exception handling in Tcl
Writing the perfect program in Tcl?
Regular Expression Substitution - Tcl
With the Shpigs and Donkeys
A weekend away - Four in a Bed returns to Happy Donkey Hill
Excellent Railfuture conference, but some setup lessons
Looking to the future at Melksham Station
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This 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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