Im wondering if there is a way to autocreate object if a property is called. An example:
<?php
echo $myObj->myProperty
?>
This code will of course fail because i did not initiate $myObj before reading the property.
What im looking for is a way to automaticly initiate $myObj based on "myObj".
Something like:
<?php
class myObj {
public myProperty = 'BlaBla';
}
echo $myObj->myProperty; //outputs BlaBla instead of failing
?>
I know about __autoload($classname) but that only works of initiating classcode with i.e. an include(), so that is not what im after.
You can use magic methods to automate stuff like that...
http://www.php.net/manual/en/language.oop5.magic.php
Just to close this question, this is what i ended up doing:
preg_match_all("/\\\$(.*?)->/si", $code, $matches);
I loop trough the code i get from database looking for any references to objects like
$xxxx->
Then i loop trough the references and create the objects
foreach($matches[1] as $key=>$value) {
$$value = Connector::loadConnector($value);
}
Where the "loadConnector is:
public function loadConnector($connector, $params = NULL) {
require_once $connector. ".php";
$c_name = $connector;
return new $c_name($params);
}
This is of course based on my file structure and it also needs some errorhandling, but so far it looks like it solves my problem :)
BR/Sune
Related
I have a class with this function:
public function loadTemplate($template)
{
return require "templates/$template.php";
}
It's fine, but I have a problem with it.
Let's say I have this code:
require('class.php');
$class = new ClassName; // ClassName is the class which contains the function loadTemplate()
$name = 'Jerry';
$class->loadTemplate('myname');
And "myname.php" is:
<?php
echo "My name is $name.";
In this case I get an error because "myname.php" is actually included in the file of the class and so $name is undefined.
How do I overcome this problem?
Not discussing whether that's the best design, here's how you can do it.
public function loadTemplate($template, $vars)
{
extract($vars);
ob_start();
require "templates/$template.php";
$viewContent = ob_get_contents();
ob_get_clean();
return $viewContent;
}
Pass your variables as an associative array:
$vars = ['name' => 'Jerry']
And then output it:
echo $class->loadTemplate('myname', $vars);
What this does is, it creates variables from the array and loads the view, but with the "ob_" functions we are capturing the output buffer and then echoing it if we want.
You could probably get away without using ob_ just by echoing the require method as you were trying. I'd say give it a go and use what you prefer.
I have two php pages and I want to use an instance of a class used in one page to another page.
My first page looks like this...
class test {
public $cfd_name;
function __construct($value) {
$this->cfd_name = $value;
}
}
$_SESSION['cc_test'] = new test('Joe');
and my second page looks like this
echo $_SESSION['cc_test']->cfd_name;
but nothing is being echoed. What am I doing wrong?
I thing a simple way is serializing the object,take a look
//includes, codes, session_start, etc...
$test = new test('Joe');
$_SESSION['cc_test'] = serialize($test);
then, in your other page you can access the object doing
$test = unserialize($_SESSION['cc_test']);
$test->cfd_name;
More info about serialize, here
In case your class is in first file is this:
class test {
public $cfd_name;
function __construct($value) {
$this->cfd_name = $value;
}
}
Just use include(file1.php) in second file
and then declare this in the second file.
session_start();
$test = new test;
$_SESSION['cc_test'] = $test0->cfd_name;
echo $_SESSION['cc_test'];
What would be a good way (along with any pros and cons) of initializing an instance of a PHP class with another object of the same class (ideally in PHP 4.x)?
Here in initialize() is essentially what I'd like to be able to do (example is extremely simplified from my use-case, see below):
$product = new Product('Widget');
$product2 = new Product('Widget #2');
$product->initialize($product2);
echo $product->name; // echos "Widget #2"
class Product {
var $name;
function __constructor($name) {
$this->name = $name;
}
function initialize($product) {
// I know this cannot be done this way in PHP.
// What are the alternatives and their pros & cons?
$this = $product;
}
}
I know this may not be "good programming practice"; with 20+ years programming experience on other languages I know a bit about what's good and what's not. So hopefully we won't get hung up on if doing this makes sense or not. I have a use-case working with some open-source code that I can't change so please just bear with me on my need for it. I'm actually trying to create an OOP wrapper around some really ugly array code buried deep in the core of WordPress.
I'm trying to write it so in future versions they can move away from the ugly array-based code because everyone will be using the new API that otherwise fully encapsulated these nasty arrays. But to make it work elegantly I need to be able to do the above (in PHP 4.x) and I don't want to write code that just copies the properties.
Thanks in advance for your help.
UPDATE
Many of you are suggesting clone but unless I misunderstand that doesn't address the question. clone makes a copy; that's not the crux of the question. I'm instead trying to get the constructed object to "become" the object passed in. At this point I'm assuming there isn't a way to do that based on the fact that 0 out of 5 answers have suggested anything but I'll wait a bit longer before selecting a best in case it was simply that my questions was unclear.
In PHP 5, object cloning might be more relevant:
http://php.net/manual/en/language.oop5.cloning.php
You can define a special __clone method.
In PHP 4 and 5, you can copy properties via:
function copy($obj)
{
foreach (get_object_vars($obj) as $key => $val)
{
$this->$key = $val;
}
}
However, you wrote "I don't want to write code that just copies the properties," and I'm not exactly sure what you mean by that.
Preferred way of doing this is to use clone keyword and to implement appropriate __clone() method if needed as mentioned by other posters. Another trick way of doing this (con: slow, pros: can be stored, sent over network and works identical in php4/5) is to serialize an object and then unserialize to create new copies of it with identical variable values.
Example:
$productCopy = unserialize(serialize($product));
EDIT: Sorry, misunderstood what you were asking for. You will have to initialize variables of the object being constructed with passed in object's variables inside of the constructor. You can't return a reference to another object from the constructor.
Example:
public function __construct($name, $object = null) {
if($object) {
foreach(get_object_vars($object) as $k => $v) {
$this->$k = $v;
}
} else {
$this->name = $name;
}
}
class Product {
var $name;
function __construct($value) {
if (is_a($value, 'Product')) {
$this->name = $value->name;
} else {
$this->name = $value;
}
}
}
Similarly, you can use instanceof instead of is_a if you prefer (depending on your PHP version).
Now you can pass a Product instance OR a name to the construct.
$product = new Product('Something');
$clone = new Product($product);
This is the best way of doing it so far:
http://www.blrf.net/howto/51_PHP__How_to_control_object_instances_in_PHP_.html
Don't use "new", instead use a static function that returns the instance you want.
I have done the following:
class MyClass {
private static $_instances;
public static function get($id) {
if (!self::$_instances) self::$_instances = Array();
$class = get_called_class();
if (!array_key_exists($class, self::$_instances)) self::$_instances[$class] = Array();
if (!is_numeric($id) || $id == '') throw new Exception('Cannot instantiate a non-numeric ID.');
if (array_key_exists($id, self::$_instances[$class])) return self::$_instances[$class][$id];
else {
self::$_instances[$class][$id] = new static($id);
return self::$_instances[$class][$id];
}
}
function __construct($id=false) {
// new instance code...
// I use $id=false to create new a db table row not load an old one
}
}
Usage:
// New instance
$a = new MyClass();
$a = new MyClass;
// MyClass with $id = 1
$b = MyClass::get(1);
$c = MyClass::get(1);
$d = new MyClass(1);
$b and $c point to the same object, while $d is a new one.
Caveats:
Garbage collection will no longer apply as your instances are stored in a static array
You'll have to change your code to use MyClass::get
Notes in my code:
New instances are called with "new static" instead of "new self" to use late static bindings.
You can set your constructor to private. This will break all your old code if you use "new", but will ensure you don't get double instances or more. You'll have to change a bit in the get function's arguments and code to allow $id=false or $id=-1 or whatever.
maybe
$product = new Product('Widget');
$product2 = new Product(null, $product);
echo $product2->name; // echos "Widget #2"
class Product {
var $name;
function __constructor($name, $product = null) {
$this->name = !empty($name) ? $name : $product->name;
}
}
Adding another answer due to it being radically different.
$product = new Product('Widget');
$product2 = new Product('Widget #2');
$product =& $product2;
echo $product->name; // echos "Widget #2"
That should work.
I am trying to assign a variable to a class in PHP, however I am not getting any results?
Can anyone offer any assistance? The code is provided below. I am trying to echo the URL as shown below, by first assigning it to a class variable.
class PageClass {
var $absolute_path = NULL;
function get_absolute_path(){
$url = $this->absolute_path;
echo $url;
}
}
$page = new PageClass();
$page->absolute_path = "http://localhost:8888/smile2/organic/";
$page->get_absolute_path(); //this should echo the URL as defined above - but does not
It also works for me.
Take a look at a live example of your code here.
However, there are a few things you should change about your class.
First, Garvey does make a good point that you should not be using var. That's the older PHP4, less OOP conscious version. Rather declare each variable public or private. In fact, you should declare each function public or private too.
Generally, most classes have private variables, since you usually only want to change the variables in specific ways. To achieve this control you usually set several public methods to allow client functions to interact with your class only in restricted predetermined ways.
If you have a getter, you'd probably want a setter, since these are usually used with private variables, like I described above.
A final note is that functions named get usually return a value. If you want to display a value, it is customary to use a name like display_path or show_path:
<?php
class PageClass
{
private $absolute_path = NULL;
public function set_absolute_path($path)
{
$this->absolute_path = $path;
}
public function display_absolute_path()
{
echo $this->absolute_path;
}
}
$page = new PageClass();
$page->set_absolute_path("http://localhost:8888/smile2/organic/");
$page->display_absolute_path();
// The above outputs: http://localhost:8888/smile2/organic/
// Your variable is now safe from meddling.
// This:
// echo $this->absolute_path;
// Will not work. It will create an error like:
// Fatal error: Cannot access private property PageClass::$absolute_path on ...
?>
Live Example Here
There's a section on classes and objects in the online PHP reference.
class PageClass {
public $absolute_path = NULL;
function get_absolute_path(){
$url = $this->absolute_path;
return $url;
}
}
$page = new PageClass();
$page->absolute_path = "http://localhost:8888/smile2/organic/";
echo $page->get_absolute_path();
Works fine for me.
Have you checked that the script and esp. the code in question is executed at all?
E.g. add some unconditional debug-output to the script. Or install a debugger like XDebug to step through the code and inspect variables.
<?php
class PageClass {
var $absolute_path = NULL; // old php4 declaration, see http://docs.php.net/oop5
function get_absolute_path() { // again old php4 declaration
$url = $this->absolute_path;
echo "debug: "; var_dump($url);
echo $url;
}
}
$page = new PageClass();
$page->absolute_path = "http://localhost:8888/smile2/organic/";
echo "debug: page->get_absolute_path\n";
$page->get_absolute_path();
I am trying to attack this problem from a completely different angle, because it doesn't look like I can achieve my goal that way.
I want to loop over the item stack in the HeadScript View Helper, and make modifications to it. The documentation for this and some of the other view helpers makes this statement:
HeadScript overrides each of append(),
offsetSet(), prepend(), and set() to
enforce usage of the special methods
as listed above. Internally, it stores
each item as a stdClass token, which
it later serializes using the
itemToString() method. This allows
you to perform checks on the items in
the stack, and optionally modify these
items by simply modifying the object
returned.
So, where is this "object returned"? I am missing a piece of the puzzle here.
Thanks for your help!
In the toString() method of Zend_View_Helper_HeadScript I noticed a foreach() loop on $this, so I tried that and it worked. Here's a HeadScript extension I wrote that illustrates the solution:
class My_View_Helper_HeadScript extends Zend_View_Helper_HeadScript
{
public function toString($indent = null)
{
$files = array();
foreach ($this as $key => $item) {
if (!empty($item->attributes)
&& array_key_exists('src', $item->attributes)
&& ('scripts' == substr($item->attributes['src'], 1, 7))) {
$files[] = $item->attributes['src'];
unset($this[$key]);
}
}
if (0 < count($files)) {
$this->prependFile('/combo.php?type=scripts&files=' . implode(',', $files));
}
return parent::toString($indent);
}
}
In Bootstrap.php the following lines to point to my helpers:
$this->bootstrap('view');
$view = $this->getResource('view');
$view->addHelperPath('My/View/Helper', 'My_View_Helper');
In my layout, I have this line:
<?php echo $this->headScript(); ?>
If my solution is unclear in any way, let me know and I'll update it to clarify.