Skip to main content

Overloading in PHP

PHP's interpretation of "overloading" is different than most object oriented languages. Overloading traditionally provides the ability to have multiple methods with the same name but different quantities and types of arguments. In PHP it's achieved through magic methods.

Remember :
1) All overloading methods must be defined as public.
2) None of the arguments of these magic methods can be passed by reference.

In PHP we have following two types of overloading and their respective functions.

Property Overloading : Property overloading is achieved through __get(), __set(), __isset() and __unset() funtions.

Property overloading only works in object context. These magic methods will not be triggered in static context. Therefore these methods should not be declared static.

<?php

require_once "DB.php";

class Persistable {
  
    private $data = array();
    private $table = "users";
  
    public function __construct($user) {
      
        $this->dbh  = DB::Connect("mysql://user:password@localhost/database");
        $query      = "SELECT id, name, email, country FROM " .$this->table . " WHERE name = ?";
        $this->data = $this->dbh->getRow($query, array($user),DB_FETCHMODE_ASSOC);
    }
  
    public function __get($member) {
      
        if (isset($this->data[$member])) {
            return $this->data[$member];
        }
    }
  
    public function __set($member, $value) {
      
        // The ID of the dataset is read-only
        if ($member == "id") {
            return;
        }
      
        if (isset($this->data[$member])) {
            $this->data[$member] = $value;
        }
    }
  
    public function __destruct() {
      
        $query = "UPDATE " . $this->table . " SET name = ?,email = ?, country = ? WHERE id = ?";
        $this->dbh->query($query, $this->name, $this->email,$this->country, $this->id);
    }
}

$class = new Persistable("Martin Jansen");
$class->name = "John Doe";
$class->country = "United States";
$class->email = "john@example.com";

?>


The code defines two special methods called __get() and __set(). __get() is called when reading the value of an undefined property, and __set() is called when changing the same property's value.

This means that whenever someone reads or writes an undefined property from the persistable class, the special methods manipulate the information in the $data property array instead of changing the class properties directly. (Remember: $data contains the row from the database!)

This is Property Overloading.


Methos Overloading : Method overloading is achieved through __call() and __callStatic() methods.

For Example :

<?php

    require_once "DB.php";

    class Persistable {
      
        private $data = array();
        private $table = "users";
        public function __construct($user) {
      
            $this->dbh = DB::Connect("mysql://user:password@localhost/database");
            $query = "SELECT id, name, email, country FROM " .$this->table . " WHERE name = ?";
            $this->data = $this->dbh->getRow($query, array($user),DB_FETCHMODE_ASSOC);
        }

        public function __get($member) {

            if (isset($this->data[$member])) {
                return $this->data[$member];
            }
        }
      
        public function __set($member, $value) {
      
            // The ID of the dataset is read-only
            if ($member == "id") {
                return;
            }
            if (isset($this->data[$member])) {
                $this->data[$member] = $value;
            }
        }
      
        public function __destruct() {
            $query = "UPDATE " . $this->table . " SET name = ?, email = ?, country = ? WHERE id = ?";
            $this->dbh->query($query, $this->name, $this->email, $this->country, $this->id);
        }
    }
  
    $class = new Persistable("Martin Jansen");
    $class->name = "John Doe";
    $class->country = "United States";
    $class->email = "john@example.com";
?>



Comments

Popular posts from this blog

Odoo/OpenERP: one2one relational field example

one2one relational field is deprecated in OpenERP version>5 but you can achieve the same using many2one relational field. You can achieve it in following two ways : 1) using many2one field in both the objects ( http://tutorialopenerp.wordpress.com/2014/04/23/one2one/ ) 2)  using inheritance by deligation You can easily find the first solution with little search over internet so let's start with 2nd solution. Scenario :  I want to create a one2one relation between two objects of openerp hr.employee and hr.employee.medical.details What I should do  i. Add _inherits section in hr_employee class ii. Add field medical_detail_id in hr_employee class class hr_employee(osv.osv):     _name = 'hr.employee'     _inherits = {' hr.employee.medical.details ': "medical_detail_id"}     _inherit = 'hr.employee'         _columns = {              'emp_code':fields.char('Employee Code', si

How to draw Dynamic Line or Timeseries Chart in Java using jfreechart library?

Today we are going to write a code to draw a dynamic timeseries-cum-line chart in java.   The only difference between simple and dynamic chart is that a dynamic event is used to create a new series and update the graph. In out example we are using timer which automatically calls a funtion after every 1/4 th second and graph is updated with random data. Let's try with the code : Note : I had tried my best to provide complete documentation along with code. If at any time anyone have any doubt or question please post in comments section. DynamicLineAndTimeSeriesChart.java import java.awt.BorderLayout; import java.awt.Color; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.Timer; import javax.swing.JPanel; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartPanel; import org.jfree.chart.JFreeChart; import org.jfree.chart.axis.ValueAxis; import org.jfree.chart.plot.XYPlot; import

pyodbc.OperationalError: ('08001', '[08001] [Microsoft][ODBC Driver 17 for SQL Server]

Recently, I faced this error in our Docker-Container environment. All the necessary packages were already installed but still, I was facing this clueless error. I search a bit and after an hour and so I found the exact reason and solution for this error. To know more about this error in detail. Please follow this Github thread. https://github.com/mkleehammer/pyodbc/issues/610 https://github.com/mkleehammer/pyodbc/issues/610#issuecomment-587523802 Solution: It's because the   server's certificate has too weak a key. In case you are using Linux env directly/not the Docker one.  Just edited /etc/ssl/openssl.cnf and change these 2 lines. MinProtocol = TLSv1.0 CipherString = DEFAULT@SECLEVEL=1 In case you are also using a container, please add these three lines to your Docker file. RUN chmod +rwx /etc/ssl/openssl.cnf RUN sed -i ' s/TLSv1.2/TLSv1/g ' /etc/ssl/openssl.cnf RUN sed -i ' s/SECLEVEL=2/SECLEVEL=1/g ' /etc/ssl/openssl.cnf Thanks!! Enjoy Programming! Refer