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PHP - Class Constructors And Properties
I'm doing some basic object coding to get my head around OOP PHP, but I've come across something I can't get to work.
I've got two identical peices of code, MyClass is defined, MyClass2 is then defined as an extension of MyClass. MyClass has three properties Public, Private and Protected. In my first example I can access Public and Protected via a method in MyClass2, this class does NOT have a constructor. The second example has a constructor but I cannot access Public: Code: [Select] <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <body> <?php ECHO "MyClass2 does not have a constructor, Public & Protected both echo correctly from MyClass2->printHello!!!<BR>"; /** * Define MyClass */ class MyClass { public $public; protected $protected; private $private; protected $varXXX; function __construct() { $this->public = "Public"; $this->protected = "Protected"; $this->private = "Private"; //$this->printHello(); } function printHello() { echo $this->public . "!!!<BR>"; echo $this->protected . "!!!<BR>"; echo $this->private . "!!!<BR>"; } } /** * Define MyClass2 */ class MyClass2 extends MyClass { // We can redeclare the public and protected method, but not private protected $protected = 'Protected2'; /* function __construct() { echo $this->public . "#<BR>"; echo $this->protected . "#<BR><BR>"; //echo $this->private . "???<BR>"; } */ function printHello() { echo $this->public . "???<BR>"; echo $this->protected . "???<BR><BR>"; //echo $this->private . "???<BR>"; } } $obj = new MyClass(); //echo $obj->public . "<BR>"; // Works //echo $obj->protected; // Fatal Error //echo $obj->private; // Fatal Error //$obj->printHello(); // Shows Public, Protected and Private $obj2 = new MyClass2(); //echo $obj2->public; // Works //echo $obj2->private; // Undefined //echo $obj2->protected; // Fatal Error $obj2->printHello(); // Shows Public, Protected2, Undefined ?> </body> </html> RESULTS IN: Public??? Protected??? Code: [Select] <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <body> <?php ECHO "MyClass2 DOES have a constructor, Public does not work from MyClass2->printHello!!!<BR>"; /** * Define MyClass */ class MyClass { public $public; protected $protected; private $private; protected $varXXX; function __construct() { $this->public = "Public"; $this->protected = "Protected"; $this->private = "Private"; //$this->printHello(); } function printHello() { echo $this->public . "!!!<BR>"; echo $this->protected . "!!!<BR>"; echo $this->private . "!!!<BR>"; } } /** * Define MyClass2 */ class MyClass2 extends MyClass { // We can redeclare the public and protected method, but not private protected $protected = 'Protected2'; function __construct() { echo $this->public . "#<BR>"; echo $this->protected . "#<BR><BR>"; //echo $this->private . "???<BR>"; } function printHello() { echo $this->public . "???<BR>"; echo $this->protected . "???<BR><BR>"; //echo $this->private . "???<BR>"; } } $obj = new MyClass(); //echo $obj->public . "<BR>"; // Works //echo $obj->protected; // Fatal Error //echo $obj->private; // Fatal Error //$obj->printHello(); // Shows Public, Protected and Private $obj2 = new MyClass2(); //echo $obj2->public; // Works //echo $obj2->private; // Undefined //echo $obj2->protected; // Fatal Error $obj2->printHello(); // Shows Public, Protected2, Undefined ?> </body> </html> RESULTS IN: # << Missing the property's contents Protected2# ??? << Missing the property's contents Protected2??? Any ideas why I cannot access the property's contents in the second example when the only difference is that it has a constructor? Similar TutorialsHi Can you call Class A's methods or properties from Class B's methods? Thanks. Hi there, I am just wondering which way is the correct one if you want to create object properties/attribute dynamically at run time using magic method __set(), __get(), for example: class Foo{ public $data = array(); public function __set($name,$value){ $this->data[$name] = $value; } public function __get($name){ if ( isset($this->data[$name]) ){ return $this->data[$name]; } } } Or using the below way class Foo{ public function assign(array $data){ foreach($data as $key => $value){ $this->$key = $value; } } } I just encountered the second way in many places and I am totally confused . Is the __set() method called implicitly by the PHP engine in the second way or what? how come this is considered as a valid code ? your usual help is appreciated I know this is a PHP site, but is it true that in Java the constructor has the same name as the class name? I went to the PHP.net manual and it has a similar set up. Is that correct? I thought there was some other convention that differed from Java? TomTees I am working with the Zend Framework and I noticed that some of the classes do not have constructor. For instance, Zend_ACL does not have a constructor. What happens with this class is instantiated? Is it just a sort of empty object? The class does not extend another class so a parent constructor is not being called. I have mysqli object in Database class base: [color=]database class:[/color] class Database { private $dbLink = null; public function __construct() { if (is_null($this->dbLink)) { // load db information to connect $init_array = parse_ini_file("../init.ini.inc", true); $this->dbLink = new mysqli($init_array['database']['host'], $init_array['database']['usr'], $init_array['database']['pwd'], $init_array['database']['db']); if (mysqli_connect_errno()) { $this->dbLink = null; } } } public function __destruct() { $this->dbLink->close(); } } Class derived is Articles where I use object dBLink in base (or parent) class and I can't access to mysqli methods (dbLink member of base class): Articles class: require_once ('./includes/db.inc'); class Articles extends Database{ private $id, .... .... $visible = null; public function __construct() { // Set date as 2009-07-08 07:35:00 $this->lastUpdDate = date('Y-m-d H:i:s'); $this->creationDate = date('Y-m-d H:i:s'); } // Setter .... .... // Getter .... .... public function getArticlesByPosition($numArticles) { if ($result = $this->dbLink->query('SELECT * FROM articles ORDER BY position LIMIT '.$numArticles)) { $i = 0; while ($ret = $result->fetch_array(MYSQLI_ASSOC)) { $arts[$i] = $ret; } $result->close(); return $arts; } } } In my front page php I use article class: include_once('./includes/articles.inc'); $articlesObj = new articles(); $articles = $articlesObj->getArticlesByPosition(1); var_dump($articles); [color=]Error that go out is follow[/color] Notice: Undefined property: Articles::$dbLink in articles.inc on line 89 Fatal error: Call to a member function query() on a non-object in articles.inc on line 89 If I remove constructor on derived class Articles result don't change Please help me I have an existing instance of my class Database, now I want to call that instance in my Session class, how would I go about doing this? Ok. I know you can pass the object of a class as an argument. Example: class A { function test() { echo "This is TEST from class A"; } } class B { function __construct( $obj ) { $this->a = $obj; } function test() { $this->a->test(); } } Then you could do: $a = new A(); $b = new B($a); Ok so that's one way i know of. I also thought that you could make a method static, and do this: (assuming class A's test is 'static') class B { function test() { A::test(); } } But that is not working. I'd like to know all possible ways of accomplishing this. Any hints are appreciated. thanks If a class has a constructor but also has a static method, if I call the static method does the constructor run so that I can use an output from the constructor in my static method? --Kenoli Hi, I need to be able to call a class based on variables. E.G. I would normally do: Code: [Select] $action = new pattern1() but i would like to be able to do it dynamicaly: Code: [Select] $patNum = 1; $action = new pattern.$patNum.() Im wondering if that's possible? If so what would the correct syntax be? Many Thanks. __call is used when a method has been called, is there anything similar to __call but for properties? I wanted to use __get, but that is only for private properties... I am working on a header for a website and the code below pulls the file location for the image. I am wondering how (if possible) I could apply the repeat-x tag to the image. I know it can be done with html/css but I'm not sure how to go about it in PHP. Thanks in advance. Code: [Select] <?php include 'db.php'; $result=mysql_query("SELECT location FROM header WHERE page='home'"); $row = mysql_fetch_row($result); echo "<img src=images/".$row[0] . "> "; ?> I have a bunch of quasi-static values that must be available to the application. Most of them are set based on settings in a configuration file. Others are based on GET, COOKIE, or SESSION values, and utilize the database to get the actual values. The values will never be written to or modified by the application, only read.
It seems to me that I could create some sort of superclass which includes static methods and properties, and I could access any value by something like superclass::get('some.value'); I could design the class so that the values are queried from the DB or obtained from a parsed file only the first time they are requested, and for future requests, retrieved from a static property.
That being said, I have been told from more than one person that I am just doing it "wrong".
Please let me know what is wrong about it.
Thank you
Hello i just want to code a function for my editor that help me to do this: i copy a page with some note and picture in my editor,when i press send bottom editor find IMG tag in and upload it in my own server i can write a function for finding IMG tag and upload,but i don't know how i have to add automatic upload to my server,is there any body here can help me for coding this? or do you know one script or editor that have this properties on it? i use my sample editor I have wizard that asks several predefined questions to find-out user needs. at the end it must offer some items based on user answers. all of available items have some properties in common and one or two specific properties. what is the best way or algorithm to do this in JavaScript? e.g: Item 1 Properties: Name Weight Color Size Item 2 Properties: Name Size Weight Item 3 Properties: Name Color Size Thanks. Hi, I'm not 100% sure if this is HTML, PHP or Javascript, but my best guess is PHP. When you upload an image on Facebook, it automatically gathers the data about the image, i.e. size, device used (i.e. Canon, iPhone), title and description. It then outputs this on the page. Is there anyway to do this with PHP, instead of having to type all the information out again and upload that with the photo to a database? Cheers. I implemented an endpoint which receives name/value pairs:
PUT someresource/123 {"name": "description", "value": "Some new description"}
I think I made a mistake, and should have implemented it as:
PUT someresource/123 {"description": "Some new description"}
The reason I think so is updating multiple properties is only (easily) possible using the later:
PUT someresource/123 {"description": "Some new description", "otherProperty": "bla bla bla"}
Assuming I am not using some 3rd party client library which only works with name/value pairs, any compelling reason why one shouldn't default to the later approach with key/values? I need to set a deep property if it is undefined or NULL such as shown below:
function setProperty($value, stdClass $config, $p1, $p2, $p3, $p4) {
if(!isset($config->$p1->$p2->$p3->$p4) || is_null($config->$p1->$p2->$p3->$p4)) {
$config->$p1->$p2->$p3->$p4=$value;
}
}
$config=json_decode(json_encode(['a'=>['b'=>['c'=>['x'=>null, 'y'=>123]], 'x'=>123],'x'=>['x'=>123], 'x'=>123]));
setProperty(321, $config, 'a','b','c','x');
setProperty(321, $config, 'a','b','c','y');
But I wish the function to work regardless of property depth and came up with the following. Recommendations for a cleaner way? Maybe I should be working with arrays and array_merge_recursive()?
function setProperty($value, stdClass $config, array $properties) {
$property=array_shift($properties);
if(!count($properties)){
if(!isset($config->$property) || is_null($config->$property)) {
$config->$property=$value;
}
}
else {
if(empty($config->$property) || !is_object($config->$property)) {
$config->$property=new \stdClass();
}
setProperty($value, $config->$property, $properties);
}
}
$config=json_decode(json_encode(['a'=>['b'=>['c'=>['x'=>null, 'y'=>123]], 'x'=>123],'x'=>['x'=>123], 'x'=>123]));
setProperty(321, $config, ['a','b','c','x']);
setProperty(321, $config, ['a','b','c','y']);
Is this an effective way of accessing the $_GET and $_POST properties? I can see that the native $_GET function has been looped through so that $varName would be for example "username" and $value would be "Jeremy". Then they are both stored into an array called $getVars? Is this the best way of doing it, if not then why? foreach($_GET as $varName=>$value) $getVars[$varName]=trim(clean($value, 100)); foreach($_POST as $varName=>$value) $postVars[$varName]=trim(clean($value, 100));[/php] Kind regards, laanes I have two classes: ## Admin.php <?php class Admin { public function __construct() { include("Config.php"); } /** * deletes a client * @returns true or false */ function deleteClient($id) { return mysql_query("DELETE FROM usernames WHERE id = '$id'"); } } ?> ## Projects.php <?php class Projects { public function __construct() { include("Config.php"); $this->admin = $admin; $this->dataFolder = $dataFolder; } /** * Deletes a project * @returns true or false */ function deleteProject($id) { $root = $_SERVER['DOCUMENT_ROOT']; $theDir = $root . $this->dataFolder; $sql = mysql_query("SELECT * FROM projectData WHERE proj_id = '$id'"); while ($row = mysql_fetch_array($sql)) { $mainFile = $row['path']; $thumb = $row['thumbnail']; if ($thumb != 'null') { unlink($theDir . "/" . substr($thumb,13)); } unlink($theDir . "/" . substr($mainFile,13)); } $delete = mysql_query("DELETE FROM projectData WHERE proj_id = '$id'"); $getDir = mysql_query("SELECT proj_path FROM projects WHERE id = '$id'"); $res = mysql_fetch_array($getDir); rmdir($theDir . "/" . $res['proj_path']); return mysql_query("DELETE FROM projects WHERE id = '$id'"); } } ?> How can I call deleteProject() from within Admin.php? Hi people! class FirstOne{ public function FunctionOne($FirstInput){ //do stuff and output value return $value1; } } Then:- class SecondOne{ public function FunctionTwo($AnotherInput){ //do stuff and output value return $value2; } } What I want to know is this, if I want to use FunctionOne() in Class SecondOne do I do it like this:- (Assume as I have instantiated the first class using $Test = new FirstOne(); ) class SecondOne{ function SecondedFunction(){ global $Test; return $Test->FunctionOne(); } public function FunctionTwo($AnotherInput){ //do stuff and output value return $value2; } public function FunctionThree(){ //some code here $this->Test->SecondedFunction();<--I think as I can omit the $this-> reference } } My point is: Do I have to do it this way or is there way of having this done through __construct() that would negate the need for a third party function? I have a version working, I just think that it is a little convoluted in the way as I have done it, so I thought I would ask you guys. Any help/advice is appreciated. Cheers Rw |
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