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In PHP, what do you mean by function overloading and function overriding. and what is the difference between both of them? couldn't figure out what is the difference between them.



Overloading is defining functions that have similar signatures, yet have different parameters. Overriding is only pertinent to derived classes, where the parent class has defined a method and the derived class wishes to override that method.

In PHP, you can only overload methods using the magic method __call.

An example of overriding:


class Foo {
   function myFoo() {
      return "Foo";

class Bar extends Foo {
   function myFoo() {
      return "Bar";

$foo = new Foo;
$bar = new Bar;
echo($foo->myFoo()); //"Foo"
echo($bar->myFoo()); //"Bar"
Thursday, December 8, 2022

From the docs:

Coalesce equal or ??=operator is an assignment operator. If the left parameter is null, assigns the value of the right paramater to the left one. If the value is not null, nothing is done.


// The folloving lines are doing the same
$this->request->data['comments']['user_id'] = $this->request->data['comments']['user_id'] ?? 'value';
// Instead of repeating variables with long names, the equal coalesce operator is used
$this->request->data['comments']['user_id'] ??= 'value';

So it's basically just a shorthand to assign a value if it hasn't been assigned before.

Wednesday, October 19, 2022

open_basedir limits all I/O operations in userspace PHP to a certain configurable subset of the filesystem, in particular to a number of directories and their subdirectories,

Its objective is mainly to avoid accidental modifications to parts of the filesystem. It can also be used to mitigate the effect of vulnerable PHP scripts on the filesystems. However, I wouldn't rely too on it from a security perspective – almost all versions of PHP come with open_basedir bypass bugs fixed (the problem being it must be manually enforced in a number of places in PHP's source code).

Friday, October 7, 2022

The clearest way to express polymorphism is via an abstract base class (or interface)

public abstract class Human{
   public abstract void goPee();

This class is abstract because the goPee() method is not definable for Humans. It is only definable for the subclasses Male and Female. Also, Human is an abstract concept — You cannot create a human that is neither Male nor Female. It’s got to be one or the other.

So we defer the implementation by using the abstract class.

public class Male extends Human{
    public void goPee(){
        System.out.println("Stand Up");


public class Female extends Human{
    public void goPee(){
        System.out.println("Sit Down");

Now we can tell an entire room full of Humans to go pee.

public static void main(String[] args){
    ArrayList<Human> group = new ArrayList<Human>();
    group.add(new Male());
    group.add(new Female());
    // ... add more...

    // tell the class to take a pee break
    for (Human person : group) person.goPee();

Running this would yield:

Stand Up
Sit Down
Sunday, December 18, 2022

Polymorphism can be achieved through overriding. Put in short words, polymorphism refers to the ability of an object to provide different behaviors (use different implementations) depending on its own nature. Specifically, depending on its position in the class hierarchy.

Method Overriding is when a method defined in a superclass or interface is re-defined by one of its subclasses, thus modifying/replacing the behavior the superclass provides. The decision to call an implementation or another is dynamically taken at runtime, depending on the object the operation is called from. Notice the signature of the method remains the same when overriding.

Method Overloading is unrelated to polymorphism. It refers to defining different forms of a method (usually by receiving different parameter number or types). It can be seen as static polymorphism. The decision to call an implementation or another is taken at coding time. Notice in this case the signature of the method must change.

Operator overloading is a different concept, related to polymorphism, which refers to the ability of a certain language-dependant operator to behave differently based on the type of its operands (for instance, + could mean concatenation with Strings and addition with numeric operands).

The example in Wikipedia is quite illustrative.

The following related questions might be also useful:

  • Polymorphism vs Overriding vs Overloading
  • Polymorphism - Define In Just Two Sentences
Saturday, December 17, 2022
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