Objects in PHP example from a Well House Consultants training course
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This example is described in the following article(s): • Introduction to Object Oriented Programming - [link] |
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Source code: allone.php Module: H108
<?php
/* This is a demonstration of Object Orientation
in PHP (version 5), in which we define a base class
of objects of type "pubtrans", which we extend to
two specific classes - "bus" and "train".
We've then got a test program - following on below
in this example (to avoid you having to download and
administer too many files!) - which creates a number
of objects of each of the types, and references
properties from them. */
class pubtrans {
/* The pubtrans class is my base class, with code that
can apply to more or less any type of public transport
(I say "more or less" since it's possible to override
in specific cases) */
private $stuff;
function __construct($from,$to,$time = "09:00") {
$this->stuff[from] = $from;
$this->stuff[to] = $to;
$this->stuff[time] = $time;
}
function getfrom() {
return $this->stuff[from];
}
function getto() {
return $this->stuff[to];
}
function setto($dn = -1) {
# This example doubles up as a getter!
if ($dn == -1) $dn = $this->stuff[to];
return $this->stuff[to] = $dn;
}
function getwhen() {
$rv = $this->stuff[time];
if ($this->stuff[isabus]) {
$rv .= " IS A BUS, MIND YOU!";
}
return $rv;
}
function bustitute() {
return $this->stuff[isabus] = 1;
}
}
class train extends pubtrans {
/* In this example, a train is a piece of public
transport with no code changes to the base class
what so ever! */
}
class bus extends pubtrans {
/* An object of type "bus" is a piece of public
transport. The only difference in this demonstration
from a base class object is that you get a warning
returned when you call up the departure time that
you've got a bus rather than anything else - perhaps
because there's a substantial number of people who
prefer train or plane to bus, and buses tend to be
much slower covering the same distance */
function getwhen() {
$rv = $this->stuff[time] . " IS A BUS, MIND YOU!";
return $rv;
}
}
/* Here is a UTILITY method, in which we're creating and
returning objects of differing types depending on the inputs
to the function. Techniques such as this are typically used
to handle data that's being loaded in from a file or a
database */
function travel($mode,$from,$to,$when) {
switch ($mode) {
case "bus":
return new bus ($from,$to,$when);
case "train":
return new train ($from,$to,$when);
}
}
/* We've got two code examples here - the first one sets up
an array of pieces of public transport of various sorts, and
then interates through them, creating a report ... */
$avail = array();
array_push ($avail,new train("Melksham","Gloucester","07:17"));
array_push ($avail,new train("Melksham","Gloucester","19:47"));
array_push ($avail,new pubtrans("B-o-A","Gloucester","17:55"));
array_push ($avail,new bus("Swindon","Gloucester","16:30"));
# No "new" in front of travel as it's not itself a constructor
# even though it calls a constructor internally and returns
# an object.
array_push ($avail,travel("bus","Trowbridge","Bath","19:45"));
array_push ($avail,travel("train","Trowbridge","Bath","19:55"));
$avail[1]->bustitute();
foreach ($avail as $option) {
$starts = $option->getfrom();
$when = $option->getwhen();
$demo_1 .= "From $starts at $when<br />\n";
}
/* ... and the second piece of code demonstrated the same
thing, but using an associative array so that we can name
rather than number the various elements. */
$abn[first] = (new train("Melksham","Gloucester","07:17"));
$abn[second] = (new train("Melksham","Gloucester","19:47"));
$abn[third] = (new pubtrans("B-o-A","Gloucester","17:55"));
$abn[fourth] = (new bus("Swindon","Gloucester","16:30"));
$abn[another] = (travel("bus","Trowbridge","Bath","19:45"));
$abn[teymore] = (travel("train","Trowbridge","Bath","19:55"));
$abn[first]->bustitute();
foreach (array_keys($abn) as $k) {
$starts = $abn[$k]->getfrom();
$when = $abn[$k]->getwhen();
$demo_2 .= "From $starts at $when<br />\n";
}
?>
<html>
<head>
<title>Public Transport OO demonstration in PHP</title>
</head>
<body>
<h1>OO Demonstration in PHP</h1>
<b>Here are the results using a regular array:</b><br /><br />
<?= $demo_1 ?><br />
<b>Here are the results using an associative array:</b><br /><br />
<?= $demo_2 ?><br />
<hr>
This is an example of Object Oriented PHP ... you can find
the source code on our web site (there will be a link below)
and you can learn all about OO PHP on
<a href=http://www.wellho.net/course/pofull.html>our training
course on the subject!</a>
</body>
</html>
Learn about this subject
This module and example are covered on the following public courses:
*
Object Oriented Programming in PHP *
PHP Programming *
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