New keyword in php

Programming Tutorials

By: Andi, Stig and Derick in PHP Tutorials on 2008-11-22 Instances of classes are created using the new keyword. What happens during the new call is that a new object is allocated with its own copies of the properties defined in the class you requested, and then the constructor of the object is called in case one was defined. The constructor is a method named __construct(), which is automatically called by the new keyword after creating the object. It is usually used to automatically perform various initializations such as property initializations. Constructors can also accept arguments, in which case, when the new statement is written, you also need to send the constructor the function parameters in between the parentheses. In PHP 4, instead of using __construct() as the constructor»s name, you had to define a method with the classes» names, like C++. This still works with PHP 5, but you should use the new unified constructor naming convention for new applications. We could pass the names of the people on the new line in the following class example :

class Person < function __construct($name) < $this->name = $name; > function getName() < return $this->name; > private $name; >; $judy = new Person("Judy") . "\n"; $joe = new Person("Joe") . "\n"; print $judy->getName(); print $joe->getName();

Tip: Because a constructor cannot return a value, the most common practice for raising an error from within the constructor is by throwing an exception.

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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:

 $obj = new Student(); echo "Name: $obj->name"; echo ""; 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 «$name» property and then a line break («»). After that, it displays the string «City: » followed by the value of the «$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:

 $obj = new Student(); echo "Name: ", $obj->name, "City: ", $obj->city; ?>

 $obj = new Student(); $x = $obj->name; $y = $obj->city; echo "Name: ", $x, "City: ", $y; ?>

In the above examples, using the statement:

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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New keyword in php

The «new» keyword is used in PHP to create new objects from classes. In this article, we will explore the syntax and usage of the «new» keyword in depth, and provide plenty of examples to help you master this important PHP feature.

Syntax

The «new» keyword is used to create new objects from classes in PHP. Here is the basic syntax for using the «new» keyword:

In this example, we use the «new» keyword to create a new object from the «MyClass» class, and assign it to the variable «$object».

Examples

Let’s look at some practical examples of how the «new» keyword can be used:

 // Example 1 class MyClass < public function sayHello( ) < echo "Hello!"; > > $object = new MyClass(); $object->sayHello(); // Output: Hello! // Example 2 class MyOtherClass < public $name; public function __construct($name) < $this->name = $name; > > $object = new MyOtherClass("John"); echo $object->name; // Output: John

In these examples, we use the «new» keyword to create new objects from classes, and then call methods or access properties on those objects.

Benefits

Using the «new» keyword has several benefits, including:

• Object-oriented programming: By using the «new» keyword to create objects from classes, you can take advantage of object-oriented programming principles to write more modular, reusable, and maintainable code.
• Code organization: By using classes and objects, you can organize your code into logical units that are easier to understand and maintain.

Conclusion

In conclusion, the «new» keyword is a powerful tool for PHP developers who are looking to write more modular, reusable, and maintainable code. It allows you to create new objects from classes, and take advantage of object-oriented programming principles to organize your code into logical units. We hope this comprehensive guide has been helpful, and we wish you the best of luck as you continue to develop your PHP skills.

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Using new Keyword in Initializers in PHP 8.1

The new keyword allows creating an instance of a class. Since PHP 8.1, the new keyword can be used in initializers (e.g. parameter default values, attribute arguments, etc.).

In versions prior to PHP 8.0, we can write the following code to initialize the default instance of the class in constructor:

interface LoggerInterface <>

class NullLogger implements LoggerInterface <>

logger = $logger ?? new NullLogger(); > >

Since PHP 8.1, the new keyword can be used inside parameter default values. We can rewrite previous code as follows:

We can use new keyword with promoted properties as well:

The new keyword cannot be used to create an instance of a class as default value for properties.

Related

PHP has the display_startup_errors directive that specifies whether the errors must be displayed that occurred.

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