Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
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.
C++ and Perl - why did they do it THAT way?

"Why did [they] do it THAT way?". It's a question often asked by the brighter and more perspective delegates on courses concerning some features of a language that I'm teaching them. And the answer "because they did" is a poor one. It's like saying to a child "because I said so" rather than looking behind the scenes for a real reason.

C++ builds up on top of C, and maintains the C syntax. So there are many things in C++ which, had it been written from a clean sheet, might not have been included. And C++ is a low level language with bit / byte / register control capability, so some of the constructs, capabilities and syntax is somewhat more cumbersome than would be ideal for many modern applications. Which is precisely why it's still much used in computation intensive type works and device drivers, etc, but has been displaced by Java and C# for many of the more mainstream uses - Java and C# both take the philosophy and approach of the C++ syntax, modifying and extending it to remove the low level and C compatibility, and other complexities who's implementation costs outweigh their usefulness in the mainstream. It's little wonder that Java and C# look very similar to each other, then, with the same starting point and same philosophy and the same market.

Perl's another language where "Why is it done THAT way" is an excellent question that is, from time to time, answered by a rather glib "for historic reasons". The use of @ as the special character to signify a list would probably NOT have been the decision made after email addresses became common, but it was an excellent choice at the time. But many (most) other answers to "why was that provided" in Perl cam come down ro a far, far better answer.

Why use \s \d and \w to represent space, digit and word characters in Perl regular expressions? Because they're very quick to type and you can get a whole lot of code in a little space ... because the \ is already designated as the 'escape' character for strings and regular expressions, and because s d and w stand for space, digit and word. But why go on to use the capital equivalent \S \D and \W for a non-space, non-digit, non-word? Now that one stumped me the first time I was asked, but I can now ask you back "what better suggestion do you have?". In practise, using the same letter in capital and lower case makes them very easy to remember once you're used to them. And the resultant regular expressions are short and elegant.

Of course, Perl is eclectic ... so you can, if you prefer, write [[:space:]] for a space character and use all of the other posix standard regular expression handlers too.

This week started with me teaching OO programming in C++ and is ending with me teaching OO programming in Perl (on our Perl for Larger Projects course). And the two philosophies and approaches make an interesting comparison. Both are right for the right application ... both are great languages and what a great deal of fun I've been having.

A series of C++ examples that put together a whole host of the facilities offered by C++ - inheritance, static, inline, public, private, const, friend, vector, namespace, new, overriding, overriding operators ... was written on the fly, and I've posted them up under our putting it all together modules. I don't have the same Perl examples to show you, as that course has still got a day to run but of course you'll find plenty from previous courses in places such as "more object in Perl" resources.
(written 2006-11-16, updated 2009-01-01)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P212 - Perl - More on Character Strings
  [453] Commenting Perl regular expressions - (2005-09-30)
  [583] Remember to process blank lines - (2006-01-31)
  [586] Perl Regular Expressions - finding the position and length of the match - (2006-02-02)
  [597] Storing a regular expression in a perl variable - (2006-02-09)
  [608] Don't expose your regular expressions - (2006-02-15)
  [737] Coloured text in a terminal from Perl - (2006-05-29)
  [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
  [1222] Perl, the substitute operator s - (2007-06-08)
  [1230] Commenting a Perl Regular Expression - (2007-06-12)
  [1251] Substitute operator / modifiers in Perl - (2007-06-28)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1510] Handling Binary data (.gif file example) in Perl - (2008-01-17)
  [1727] Equality and looks like tests - Perl - (2008-07-29)
  [1735] Finding words and work boundaries (MySQL, Perl, PHP) - (2008-08-03)
  [1947] Perl substitute - the e modifier - (2008-12-16)
  [2230] Running a piece of code is like drinking a pint of beer - (2009-06-11)
  [2379] Making variables persistant, pretending a database is a variable and other Perl tricks - (2009-08-27)
  [2657] Want to do a big batch edit? Nothing beats Perl! - (2010-03-01)
  [2801] Binary data handling with unpack in Perl - (2010-06-10)
  [2834] Teaching examples in Perl - third and final part - (2010-06-27)
  [2874] Unpacking a Perl string into a list - (2010-07-16)
  [2877] Further more advanced Perl examples - (2010-07-19)
  [2993] Arrays v Lists - what is the difference, why use one or the other - (2010-10-10)
  [3059] Object Orientation in an hour and other Perl Lectures - (2010-11-18)
  [3100] Looking ahead and behind in Regular Expressions - double matching - (2010-12-23)
  [3322] How much has Perl (and other languages) changed? - (2011-06-10)
  [3332] DNA to Amino Acid - a sample Perl script - (2011-06-24)
  [3411] Single and double quotes strings in Perl - what is the difference? - (2011-08-30)
  [3546] The difference between dot (a.k.a. full stop, period) and comma in Perl - (2011-12-09)
  [3630] Serialsing and unserialising data for storage and transfer in Perl - (2012-02-28)
  [3650] Possessive Regular Expression Matching - Perl, Objective C and some other languages - (2012-03-12)
  [3707] Converting codons via Amino Acids to Proteins in Perl - (2012-04-25)
  [3927] First match or all matches? Perl Regular Expressions - (2012-11-19)
  [4452] Binary data handling - Python and Perl - (2015-03-09)

P208 - Perl - Lists
  [28] Perl for breakfast - (2004-08-25)
  [140] Comparison Chart for Perl programmers - list functions - (2004-12-04)
  [230] Course sizes - beware of marketing statistics - (2005-02-27)
  [240] Conventional restraints removed - (2005-03-09)
  [355] Context in Perl - (2005-06-22)
  [463] Splitting the difference - (2005-10-13)
  [560] The fencepost problem - (2006-01-10)
  [622] Queues and barrel rolls in Perl - (2006-02-24)
  [762] Huge data files - what happened earlier? - (2006-06-15)
  [773] Breaking bread - (2006-06-22)
  [968] Perl - a list or a hash? - (2006-12-06)
  [1304] Last elements in a Perl or Python list - (2007-08-16)
  [1316] Filtering and altering Perl lists with grep and map - (2007-08-23)
  [1703] Perl ... adding to a list - end, middle, start - (2008-07-09)
  [1828] Perl - map to process every member of a list (array) - (2008-10-09)
  [1917] Out of memory during array extend - Perl - (2008-12-02)
  [1918] Perl Socket Programming Examples - (2008-12-02)
  [2067] Perl - lists do so much more than arrays - (2009-03-05)
  [2226] Revision / Summary of lists - Perl - (2009-06-10)
  [2295] The dog is not in trouble - (2009-07-17)
  [2484] Finding text and what surrounds it - contextual grep - (2009-10-30)
  [2813] Iterating over a Perl list and changing all items - (2010-06-15)
  [2833] Fresh Perl Teaching Examples - part 2 of 3 - (2010-06-27)
  [2996] Copying - duplicating data, or just adding a name? Perl and Python compared - (2010-10-12)
  [3400] $ is atomic and % and @ are molecular - Perl - (2011-08-20)
  [3548] Dark mornings, dog update, and Python and Lua courses before Christmas - (2011-12-10)
  [3669] Stepping through a list (or an array) in reverse order - (2012-03-23)
  [3870] Writing more maintainable Perl - naming fields from your data records - (2012-09-25)
  [3906] Taking the lead, not the dog, for a walk. - (2012-10-28)
  [3939] Lots of ways of doing the same thing in Perl - list iteration - (2012-12-03)
  [4609] Mapping an array / list without a loop - how to do it in Perl 6 - (2016-01-03)

C231 - C and C based languages - Introduction to C++
  [317] Programming languages - a comparison - (2005-05-20)
  [318] Choosing a theme - (2005-05-20)
  [336] Targetted Advertising - (2005-06-05)
  [2004] Variable Scope in C++ - (2009-01-22)
  [2169] When should I use OO techniques? - (2009-05-11)
  [2845] Objects and Inheritance in C++ - an easy start - (2010-07-01)
  [3052] Getting your C++ program to run - (2010-11-15)
  [3053] Make - automating the commands for building and installing - (2010-11-16)
  [3069] Strings, Garbage Collection and Variable Scope in C++ - (2010-11-25)
  [3250] C++ - how we teach the language and the concepts behind the language - (2011-04-17)
  [4466] Moving from C to C++ - Structured to Object Oriented - a lesson for engineers - (2015-03-28)
  [4561] Hello World in C++ - a first program, with the process explained - (2015-10-30)
  [4562] Left shift operator on an output stream object - C++ - (2015-10-30)


Back to
Hotel door furniture
Previous and next
or
Horse's mouth home
Forward to
Presenting Melksham - for a weekend away in Wiltshire
Some other Articles
A tale of a wee wall
Before and After - Well House Manor
-> , >= and => in Perl
Presenting Melksham - for a weekend away in Wiltshire
C++ and Perl - why did they do it THAT way?
Hotel door furniture
Training rooms to learn Open Source programming
C++ - just beyond the basics. More you can do
The LAMP Cookbook - Linux, Apache, MySQL, PHP / Perl
Why shouldn't I spam?
4759 posts, page by page
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, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page


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.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2021: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/928_C-an ... -way-.html • PAGE BUILT: Sun Oct 11 16:07:41 2020 • BUILD SYSTEM: JelliaJamb