aidan Fri Oct 29 23:39:07 2004 EDT
Modified files:
/phpdoc/en/language/oop5 patterns.xml
Log:
Better examples
http://cvs.php.net/diff.php/phpdoc/en/language/oop5/patterns.xml?r1=1.1&r2=1.2&ty=u
Index: phpdoc/en/language/oop5/patterns.xml
diff -u phpdoc/en/language/oop5/patterns.xml:1.1
phpdoc/en/language/oop5/patterns.xml:1.2
--- phpdoc/en/language/oop5/patterns.xml:1.1 Fri Oct 29 07:28:28 2004
+++ phpdoc/en/language/oop5/patterns.xml Fri Oct 29 23:39:06 2004
@@ -1,5 +1,5 @@
<?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.1 $ -->
+<!-- $Revision: 1.2 $ -->
<sect1 id="language.oop5.patterns">
<title>Patterns</title>
<para>
@@ -19,10 +19,9 @@
<programlisting role="php">
<![CDATA[
<?php
-class DB {
- // ... Other methods
-
- // The Factory Method
+class Example
+{
+ // The factory method
function &factory($type)
{
if (include_once 'Drivers/' . $type . '.php') {
@@ -38,17 +37,18 @@
</programlisting>
<para>
Defining this method in a class allows drivers to be loaded on the
- fly. Loading a <literal>MySQL</literal> and a
+ fly. If the <literal>Example</literal> class was a database
+ abstraction class, loading a <literal>MySQL</literal> and
<literal>SQLite</literal> driver could be done as follows:
</para>
<programlisting role="php">
<![CDATA[
<?php
// Load a MySQL Driver
-$db_mysql = DB::factory('MySQL');
+$mysql = Example::factory('MySQL');
// Load a SQLite Driver
-$db_sqlite = DB::factory('SQLite');
+$sqlite = Example::factory('SQLite');
?>
]]>
</programlisting>
@@ -69,30 +69,52 @@
<programlisting role="php">
<![CDATA[
<?php
-function &singleton($class)
-{
- // Declare a static variable to hold the object instance
- static $instance;
-
- // If the instance is not there create one
- if (!isset($instance)) {
- $instance = new $class;
+class Example
+{
+ // Hold an instance of the class
+ static private $instance;
+
+ // A private constructor
+ private function __construct()
+ {
+ echo 'I am constructed';
}
- return($instance);
+ // The singleton method
+ static public function singleton()
+ {
+ if (!isset(self::$instance)) {
+ $c = __CLASS__;
+ self::$instance = new $c;
+ }
+
+ return self::$instance;
+ }
+
+ // Example method
+ public function bark()
+ {
+ echo 'Woof!';
+ }
}
?>
]]>
</programlisting>
<para>
- This allows a single instance of any class to be retrieved.
- Loading an example <literal>DB</literal> could be done like so:
+ This allows a single instance of the <literal>Example</literal>
+ class to be retrieved.
</para>
<programlisting role="php">
<![CDATA[
<?php
-$db = singleton('DB');
+// This would fail because the constructor is private
+$test = new Example;
+
+// This will always retrieve a single instance of the class
+$test = Example::singleton();
+$test->bark();
+
?>
]]>
</programlisting>
