Sorting objects in PHP

The OO model in PHP is very powerful indeed - and much more code is now written using the facilities it offers than was the case a year or two ago. On yesterday's Object Oriented Programming in PHP course, I wrote a new example that nicely brought together many of the facilities on offer - you can see the full sample code here.

One very common requirement is to sort an array of objects in PHP, and if you just use the regular sort function, you'll end up sorting (I think) based on the memory address at which they are held. That is never what you want! Instead - you should use usort

Here's my example of a call to usort:

usort($wellhousemanor,array("transact","mvf"));

And that sorts an array of objects in the $wellhousemanor array, using the static member function called mvf in the class transact to compare pairs of records. All you (as the application programmer) need do is make the call in this (rather curious, it must be said) way. If you're the programmer writing the class, you simply provide a method of the given name that takes two parameters and return negative if the first object passed should come earlier, positive if the second object passed should come earlier, and zero to indicate that the objects are equally ranked for sorting.

Here's my example comparator:

static function mvf($first,$second) {

if ($first->getvalue() > $second->getvalue()) return 1;

if ($first->getvalue() < $second->getvalue()) return -1;

return 0;

}

Q: I'm a PHP programmer - should I use objects these days?

A: In most cases YES - exceptions are minimum maintainance jobs on older code, and tiny applications where you'll never have more than a few lines of PHP. And even if you're not writing your own objects, chances are that you'll use objects that other people have written and perhaps contributed via something like PEAR.
(written 2008-10-04)

Associated topics are indexed under

H108 - Objects in PHP
  [4073] Learning about Object Orientation in PHP - a new set of examples - (2013-04-28)
  [4057] stdClass in PHP - using an object rather than an associative array - (2013-04-02)
  [3953] Objects in PHP - Revision - (2012-12-16)
  [3843] Caching Design Patterns - (2012-08-20)
  [3841] Copying, duplicating, cloning an object in PHP - (2012-08-18)
  [3840] Autoload in PHP - (2012-08-17)
  [3609] How do classes relate to each other? Associated Classes - (2012-02-12)
  [3608] Design Patterns - what are they? Why use them? - (2012-02-12)
  [3607] Designing your application - using UML techniques - (2012-02-11)
  [3211] Computer Graphics in PHP - World (incoming data) to Pixel (screen) conversion - (2011-03-24)
  [3210] Catchable fatal error in PHP ... How to catch, and alternative solutions such as JSON - (2011-03-22)
  [3142] Private and Public - and things between - (2011-01-22)
  [2922] Getting the OO design write - with PHP a example - (2010-08-14)
  [2921] Does copying a variable duplicate the contents? - (2010-08-14)
  [2774] PHP - Object Oriented Design in use - (2010-05-21)
  [2741] What is a factory? - (2010-04-26)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2680] Static class members in PHP - a documented example - (2010-03-16)
  [2641] Object Oriented Programming in PHP - (2010-02-19)
  [2632] Shipping a test harness with your class in PHP - (2010-02-12)
  [2435] Serialization - storing and reloading objects - (2009-10-04)
  [2434] Abstract classes, Interfaces, PHP and Java - (2009-10-03)
  [2380] Object Oriented programming - a practical design example - (2009-08-27)
  [2172] PHP4 v PHP5 - Object Model Difference - (2009-05-11)
  [2171] Cleaning up redundant objects - (2009-05-11)
  [2169] When should I use OO techniques? - (2009-05-11)
  [2160] PHP - getclass v instanceof - (2009-05-07)
  [1925] Introduction to Object Oriented Programming - (2008-12-06)
  [1819] Calling base class constructors - (2008-10-03)
  [1682] Accounts in PHP - an OO demo - (2008-06-19)
  [1535] OO PHP demonstration - comparing objects and more - (2008-02-08)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1153] Object Oriented Model - a summary of changes from PHP4 to PHP5 - (2007-04-18)
  [1027] Cue the music, I'm happy. - (2007-01-09)
  [836] Build on what you already have with OO - (2006-08-17)
  [720] Planning a hotel refurb - an example of a Gant chart in PHP - (2006-05-14)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [485] North, Norther and Northest - PHP 5 Objects - (2005-11-04)
  [421] Don't repeat code - use loops or functions - (2005-08-21)
  [343] Should I use structured or object oriented? - (2005-06-10)
  [205] PHP5 lets you say no - (2005-02-07)
  [124] PHP v Java - (2004-11-20)
  [67] Object Oriented Programming in PHP - (2004-09-29)

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