PHP new keyword: Create an Object from a Class

The PHP "new" keyword is used when we need to create a new object from a class. For example:

<?php
   class Student
   {
      public $name = "Lucas";
      public $city = "Amsterdam";
   }
   
   $obj = new Student();
   
   echo "Name: $obj->name";
   echo "<BR>";
   echo "City: $obj->city";
?>

This PHP code defines a class called "Student". The class has two properties, namely "$name" and "$city" which are both initialized to string values of "Lucas" and "Amsterdam" respectively. Then, an object of the class "Student" is created using the "new" keyword and assigned to the variable "$obj".

Finally, the code outputs the values of the object's properties using the "echo" statement. It displays the string "Name: " followed by the value of the "$name" property and then a line break ("<BR>"). After that, it displays the string "City: " followed by the value of the "$city" property.

The output of the above PHP example on the "new" keyword is shown in the snapshot given below:

In other words, we can say that the PHP "new" keyword creates class instances. PHP creates a class-specific object and returns a reference when the new keyword is used.

The above example can also be written in this way:

<?php
   class Student {
      public $name = "Lucas";
      public $city = "Amsterdam"; }
   
   $obj = new Student();
   
   echo "Name: ", $obj->name, "<BR>City: ", $obj->city;
?>

Or

<?php
   class Student {
      public $name = "Lucas";
      public $city = "Amsterdam";
   }
   
   $obj = new Student();
   
   $x = $obj->name;
   $y = $obj->city;
   
   echo "Name: ", $x, "<BR>City: ", $y;
?>

In the above examples, using the statement:

$obj = new Student();

An object named $obj is created of type Student class.

Advantages of the "new" keyword in PHP

• The "new" keyword gives your code a lot of flexibility by allowing you to create multiple instances of the same class with different properties and values.
• The "new" keyword helps to create reusable code by enabling you to create and instantiate classes. Object-oriented programming (OOP) promotes code reuse.
• The "new" keyword facilitates the division of code into modular chunks that are simpler to comprehend, maintain, and troubleshoot.
• By encapsulating data and functionality within an object using the "new" keyword, naming conflicts can be avoided and the code can be made more secure.

Disadvantages of the "new" keyword in PHP

• When you create an instance of a class using the "new" keyword, your code becomes closely related to that class. As a result, any changes to the class might necessitate changes to all the code that depends on it, which can make your code less flexible and more difficult to maintain.
• Using the "new" keyword can make your code more challenging to test because it can be challenging to isolate and mock dependencies. This may result in more unstable and unreliable tests.
• PWhen compared to other ways of creating objects in PHP, using the "new" keyword to create a new instance of a class can be somewhat slow. Performance problems in high-traffic applications may result from this.
• Using dependency injection, a crucial technique for producing flexible and reusable code, can be challenging when the "new" keyword is used.

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