How to refactor PHP5.6 code to adapt to PHP7.4 compatibility changes?

How to refactor PHP5.6 code to adapt to PHP7.4 compatibility changes?

As time goes by, programming languages ​​are constantly updated and evolved, and the release of new versions usually brings some compatibility changes. As a widely used scripting language, PHP has also introduced many changes in the upgrade process from PHP5.6 to PHP7.4. In order to ensure that the code can run properly in the new version, it is necessary for us to adapt and refactor the code.

The following will introduce some refactoring techniques to help you refactor PHP5.6 code into code that adapts to PHP7.4 compatibility changes.

1. Replace outdated functions and features

1. Replace outdated constructors
   PHP7.4 removes support for class methods and constructors with the same class name , that is, it is forbidden to use __construct as the method name of the constructor. During the refactoring process, you need to change the method defined as __construct to use the class name to name the constructor, for example: class ClassName { public function ClassName() {...} }.
2. Replace expired error handling functions
   In PHP7.4, some expired error handling functions are no longer valid, including ereg(), ereg_replace(), eregi(), eregi_replace(), split () and spliti() functions. During the reconstruction process, you need to use alternative functions such as preg_match(), preg_replace(), preg_match_all(), etc.
3. Replace expired global variable functions
   The original global variable functions such as $HTTP_GET_VARS, $HTTP_POST_VARS, $HTTP_SESSION_VARS, $HTTP_COOKIE_VARS, etc. were abandoned in PHP5.4 and removed in PHP7.4. During the reconstruction process, you need to use $_GET, $_POST, $_SESSION, $_COOKIE and other substitution variables.

2. Modify the parameters of functions, methods and classes using

1. Modify function parameters by reference transfer
   Before PHP7.4, function parameters were usually passed by reference. However, PHP 7.4 removed support for unnecessary passing by reference. During refactoring, unnecessary reference symbols (&) should be removed from function definitions.
2. Modify method parameter passing
   Before PHP7.4, class method parameters were passed by value by default. If you need to use reference passing, you need to specify it clearly when the function is declared. During the refactoring process, the parameter passing method of the class method needs to be checked to ensure that it is modified as needed.
3. Modify class attribute access guidance
   Before PHP7.4, access to class attributes could be achieved by using $this->attr. However, PHP 7.4 removed support for implicit references to uninitialized properties. During refactoring, you need to ensure that the properties of the class are initialized before use.

3. Update functions and method calls

1. Update expired function calls
   Before PHP7.4, some expired functions may have been used. During the reconstruction process, the corresponding new functions need to be used to replace the expired functions.
2. Update class method calling
   PHP7.4 introduced a new class method calling syntax, namely $obj::method(). During the refactoring process, you should check how class methods are called to see if new syntax is needed.
3. Updated handling of function and method return values
   Prior to PHP7.4, unsafe assumptions may have been made about function and method return values, such as operating on them directly as arrays or objects. During the refactoring process, appropriate modifications need to be made to the handling of function and method return values.

The following is a sample code that demonstrates how to perform the above refactoring steps:

class User {
    private $name;
    
    public function __construct($name) {
        $this->name = $name;
    }
    
    public function getName() {
        return $this->name;
    }
}

$user = new User("John");
echo $user->getName();

The above sample code can be refactored to adapt to PHP7.4 code:

class User {
    private string $name;
    
    public function __construct(string $name) {
        $this->name = $name;
    }
    
    public function getName(): string {
        return $this->name;
    }
}

$user = new User("John");
echo $user->getName();

In the above code example, we adapted the code to the compatibility changes of PHP7.4 by updating the definition of the constructor, adding attribute type declarations, and clarifying the method return type.

Summary:

Refactoring PHP5.6 code to adapt to PHP7.4 compatibility changes is a necessary process, and it is also an important step to maintain code health and performance. By replacing outdated functions and features, modifying the parameter usage of functions, methods and classes, and updating function and method calls, we can help us successfully refactor. However, the refactoring process should be carried out according to the circumstances of the specific project. It is recommended to back up the original code before refactoring and refactor step by step to ensure the correctness and stability of the code.

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