note 101545 added to function.class-exists
| From: | contact at rahulprasad dot com | Date: | Thu, 23 Dec 2010 16:25:47 +0000 |
| Subject: | note 101545 added to function.class-exists | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-175174@lists.php.net to get a copy of this message | ||
Declare a class only if does not exists.
------------------Example 1------------------
<?php
if(!class_exists('MyClass')) {
class MyClass {
public function __construct() {
echo "<br />Hello<br />";
}
}
}
$x = new MyClass();
?>
Output:
Hello
------------------Example 2------------------
<?php
class MyClass {
public function __construct() {
echo "<br />Hi<br />";
}
}
if(!class_exists('MyClass')) {
class MyClass {
public function __construct() {
echo "<br />Hello<br />";
}
}
}
?>
Output:
Hi
------------------Usage------------------
If any class is not supported in older version of PHP you can check it before creating it.
Like PHP version less than 5.1 does not support InvalidArgumentException class, So before using it
you can make sure it does exists but using class_exists()
<?php
if(!class_exists(InvalidArgumentException)) {
class InvalidArgumentException extends Exception {
}
}
?>
----
Server IP: 69.147.83.197
Probable Submitter: 117.254.255.36
----
Manual Page -- http://www.php.net/manual/en/function.class-exists.php
Edit -- https://master.php.net/note/edit/101545
Del: integrated -- https://master.php.net/note/delete/101545/integrated
Del: useless -- https://master.php.net/note/delete/101545/useless
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Del: spam -- https://master.php.net/note/delete/101545/spam
Del: non-english -- https://master.php.net/note/delete/101545/non-english
Del: in docs -- https://master.php.net/note/delete/101545/in+docs
Del: other reasons-- https://master.php.net/note/delete/101545
Reject -- https://master.php.net/note/reject/101545
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