Training, Open Source Programming Languages

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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.
Returning multiple values from a function call in various languages - a comparison

I've always thought it a bit odd that you call a function with any number of parameters, and yet it returns a single value; in Java, C or C++ you declare a return type (void if there is not to be anything returned) and you are then constrained by that specification. There are, of course, other ways of returning data too. Most languages support some sort of global capability, or "call by reference" in which you can modify the incoming data and that alteration will also change the variable's contents as seen in the calling code. And in some languages such as Perl, special variables may be set within a function and the accessed outside.

But some languages do support multiple returns:

Ruby. If you return an array, and assign the result to more than one variable (in a comma separated list), the array will be unwrapped:
  smaller,larger = ben 10,20,30
See full code example [here]

Python. If you return a tuple, it can be split out into multuple variables:
  smaller,larger = ben(10,20,30)
See [here] - a previous article than includes a complete example

Perl. You can return a list (of several items) of a scalar from a sub, and you can use the misnamed wantarray function within the sub to determine the return type. You assign the returned value into a scalar or a list (remembering that assigning a list to a scalar will give you the length of the list!). There's an example in our course material [here] and you can assign the results to a named list of scalars if you wish:
  ($smaller,$larger) = ben(10,20,30)

PHP. If you return an array, you can assign it into a list function and store each of the returned members into its own variable:
  list($smaller, $larger) = ben(10,20,20);
You'll find this used in our real live global site index, for which we publish the source code (passwords changed!) [here]. There's a shorter example that uses this [here].

Before you start returning multiple values, though, think carefully. Should you be returning a single object instead?. A regular expression match in Perl returns a list of matched strings (if used in a list context). But in other languages (though you may have the option of multiple values back) you can also get back a single object from which you can request the elements that you need.
(written 2011-02-06, updated 2011-02-10)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y105 - Python - Functions, Modules and Packages
  [96] Variable Scope - (2004-10-22)
  [105] Distance Learning - (2004-10-31)
  [294] Python generator functions, lambdas, and iterators - (2005-04-28)
  [303] Lambdas in Python - (2005-05-06)
  [308] Call by name v call by value - (2005-05-11)
  [340] Code and code maintainance efficiency - (2005-06-08)
  [386] What is a callback? - (2005-07-22)
  [418] Difference between import and from in Python - (2005-08-18)
  [561] Python's Generator functions - (2006-01-11)
  [668] Python - block insets help with documentation - (2006-04-04)
  [745] Python modules. The distribution, The Cheese Shop and the Vaults of Parnassus. - (2006-06-05)
  [749] Cottage industry or production line data handling methods - (2006-06-07)
  [775] Do not duplicate your code - (2006-06-23)
  [821] Dynamic functions and names - Python - (2006-08-03)
  [900] Python - function v method - (2006-10-20)
  [912] Recursion in Python - (2006-11-02)
  [913] Python - A list of methods - (2006-11-03)
  [949] Sludge off the mountain, and Python and PHP - (2006-11-27)
  [959] It's the 1st, not the 1nd 1rd or 1th. - (2006-12-01)
  [1134] Function / method parameters with * and ** in Python - (2007-04-04)
  [1163] A better alternative to cutting and pasting code - (2007-04-26)
  [1202] Returning multiple values from a function (Perl, PHP, Python) - (2007-05-24)
  [1464] Python Script - easy examples of lots of basics - (2007-12-08)
  [1784] Global - Tcl, PHP, Python - (2008-09-03)
  [1790] Sharing variables with functions, but keeping them local too - Python - (2008-09-09)
  [1869] Anonymous functions (lambdas) and map in Python - (2008-11-04)
  [1870] What to do with a huge crop of apples - (2008-11-04)
  [1871] Optional and named parameters in Python - (2008-11-05)
  [1879] Dynamic code - Python - (2008-11-11)
  [2011] Conversion of OSI grid references to Eastings and Northings - (2009-01-28)
  [2439] Multiple returns from a function in Python - (2009-10-06)
  [2440] Optional parameters to Python functions - (2009-10-07)
  [2481] Sample code with errors in it on our web site - (2009-10-29)
  [2506] Good example of recursion in Python - analyse an RSS feed - (2009-11-18)
  [2520] Global and Enable - two misused words! - (2009-11-30)
  [2718] Python - access to variables in the outer scope - (2010-04-12)
  [2766] Optional and named parameters to Python functions/methods - (2010-05-15)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2929] Passing a variable number of parameters in to a function / method - (2010-08-20)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2998] Using an exception to initialise a static variable in a Python function / method - (2010-10-13)
  [3280] Passing parameters to Python functions - the options you have - (2011-05-07)
  [3459] Catching the fishes first? - (2011-09-27)
  [3464] Passing optional and named parameters to python methods - (2011-10-04)
  [3472] Static variables in functions - and better ways using objects - (2011-10-10)
  [3474] Python Packages - groupings of modules. An introduction - (2011-10-11)
  [3662] Finding all the unique lines in a file, using Python or Perl - (2012-03-20)
  [3695] Functions are first class variables in Lua and Python - (2012-04-13)
  [3766] Python timing - when to use a list, and when to use a generator - (2012-06-16)
  [3852] Static variables in Python? - (2012-08-29)
  [3885] Default local - a good choice by the author of Python - (2012-10-08)
  [3931] Optional positional and named parameters in Python - (2012-11-23)
  [3945] vargs in Python - how to call a method with unknown number of parameters - (2012-12-06)
  [4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
  [4161] Python varables - checking existance, and call by name or by value? - (2013-08-27)
  [4212] Python functions - an introduction to how they work - (2013-11-16)
  [4361] Multiple yields and no loops in a Python generator? - (2014-12-22)
  [4407] Python - even named code blocks are objects - (2015-01-28)
  [4410] A good example of recursion - a real use in Python - (2015-02-01)
  [4441] Reading command line parameters in Python - (2015-02-23)
  [4448] What is the difference between a function and a method? - (2015-03-04)
  [4645] What are callbacks? Why use them? An example in Python - (2016-02-11)
  [4662] Recursion in Python - the classic example - (2016-03-07)
  [4719] Nesting decorators - (2016-11-02)
  [4722] Embedding more complex code into a named block - (2016-11-04)
  [4724] From and Import in Python - where is the module loaded from? - (2016-11-06)

R104 - Ruby - Control Structures
  [960] 1st, 2nd, 3rd revisited in Ruby - (2006-12-02)
  [962] Breaking a loop - Ruby and other languages - (2006-12-03)
  [985] Equality in Ruby - == eql? and equal? - (2006-12-14)
  [995] Ruby's case - no break - (2006-12-17)
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [1582] Ruby, C, Java and more - getting out of loops - (2008-03-19)
  [1587] Some Ruby programming examples from our course - (2008-03-21)
  [1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
  [1738] Clean code, jump free (Example in Lua) - (2008-08-06)
  [1887] Ruby Programming Course - Saturday and Sunday - (2008-11-16)
  [1891] Ruby to access web services - (2008-11-16)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [2287] Learning to program in Ruby - examples of the programming basics - (2009-07-15)
  [2471] A short form of if ... then ... else - (2009-10-23)
  [2619] Passing code to procedures and yield in Ruby - (2010-02-02)
  [2711] For loop - checked once, or evety time? Ruby v Perl comparison and contrast - (2010-04-07)
  [2892] Alternative loops and conditionals in Ruby and Perl - (2010-07-28)
  [2975] Why do I need brackets in Ruby ... or Perl, Python, C or Java - (2010-09-29)
  [3156] Splitting data reading code from data processing code - Ruby - (2011-02-04)
  [3158] Ruby training - some fresh examples for string handling applications - (2011-02-05)
  [3200] How a for loop works Java, Perl and other languages - (2011-03-12)
  [3253] Is this number between? Does this list include? - Ruby - (2011-04-18)
  [3254] Multiple inputs, multiple out, ruby functions - (2011-04-19)
  [3397] Does a for loop evaluate its end condition once, or on every iteration? - (2011-08-18)
  [3422] Assigning values to variables within other statements - Ruby - (2011-09-07)
  [3619] Ruby v Perl - a comparison example - (2012-02-21)
  [3620] Finding the total, average, minimum and maximum in a program - (2012-02-22)
  [3769] Muttable v immutable and implications - Ruby - (2012-06-20)
  [4322] Learning to Program - the conditional statement (if) - (2014-11-21)
  [4323] Learning to program - Loop statements such as while - (2014-11-22)
  [4370] Conditionals, loops and methods in Ruby - a primer with simple examples - (2014-12-29)
  [4402] Finding sum, minimum, maximum and average in Python (and Ruby) - (2015-01-19)
  [4503] Separating your code for easier testing, understanding and re-use; example in Ruby - (2015-06-02)
  [4504] Where does Ruby load modules from, and how to load from current directory - (2015-06-03)
  [4674] Alternating valuses / flip-flop / toggle - example in Ruby - (2016-05-17)

P303 - Perl - Miscellany
  [2219] Configuring httpd, or Tomcat, to run CGI scripts in Perl - (2009-06-05)
  [2427] Operator overloading - redefining addition and other Perl tricks - (2009-09-27)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)
  [2877] Further more advanced Perl examples - (2010-07-19)
  [3012] Exception handling in Perl - using eval - (2010-10-23)

H308 - PHP - Searches, and search engines
  [1020] Parallel processing in PHP - (2007-01-03)
  [1735] Finding words and work boundaries (MySQL, Perl, PHP) - (2008-08-03)
  [2137] Reaching the right people with your web site - (2009-04-23)
  [2166] Crossrefering documents with uniqueness and inconsistency issues - PHP proof of concept demo - (2009-05-10)
  [2631] How to show a large result set page by page in PHP - (2010-02-11)
  [3163] Twitter - the special use of @ # and http: in tweets - (2011-02-09)
  [4401] Selecting RECENT and POPULAR news and trends for your web site users - (2015-01-19)

H109 - PHP - Input / Output
  [114] Relative or absolute milkman - (2004-11-10)
  [616] printf - a flawed but useful function - (2006-02-22)
  [653] Easy feed! - (2006-03-21)
  [709] Handling huge data files in PHP - (2006-05-04)
  [997] Most recent file in a directory - PHP - (2006-12-18)
  [1094] PHP fread - truncated data - (2007-02-27)
  [1096] Sample script - FTP to get a file from within PHP - (2007-03-01)
  [1113] File and URL reading in PHP - (2007-03-20)
  [1442] Reading a file multiple times - file pointers - (2007-11-23)
  [1780] Server overloading - turns out to be feof in PHP - (2008-09-01)
  [2964] An introduction to file handling in programs - buffering, standard in and out, and file handles - (2010-09-21)
  [3029] PHP data sources - other web servers, large data flows, and the client (browser) - (2010-11-04)
  [3424] Divide 10000 by 17. Do you get 588.235294117647, 588.24 or 588? - Ruby and PHP - (2011-09-08)
  [4483] Moving from mysql to mysqli - simple worked example - (2015-05-03)


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Extra courses - Advanced PHP, MySQL and Lua
Returning multiple values from a function call in various languages - a comparison
A new monopoly on the ferry to Northern Ireland
Rake - a build system using code written in Ruby
Changing a class later on - Ruby
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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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