What are named arguments in PHP?

PHP is excellent for generating dynamic web pages and apps. PHP scripts are executed on the server to generate HTML content, which is then delivered to the client’s web browser.

PHP 8 is a major update of the PHP programming language that includes several upgrades, new features, and speed increases, such as the named arguments feature.

Why do we need named arguments?

Named arguments allow us to send parameters to a function by giving the parameter name, making function calls easier to understand as they are not dependent on argument order. This improves code readability and makes it easier to maintain, particularly for functions with many arguments.

Key features

Here are some key aspects of the named arguments feature:

  • Named arguments in PHP 8 provide a more flexible way to pass arguments to functions.

  • Instead of relying on the order of parameters, we can specify the parameter name followed by the corresponding value.

  • This enhances code readability, especially for functions with many parameters or optional parameters.

Code example

In this PHP example, we have a function called greet that takes three parameters: $name, $age, and an optional parameter $greeting. Next, we will call this function with a random arrangement of input parameters, and the function will then print a message using these parameters. Let’s see what output we get.

<?php
function greet($name, $age, $greeting = "Hello") {
    echo "$greeting, $name! You are $age years old.";
}
// Normal function call in PHP
greet("Hi", "Zack", 25);
?>

Let’s get into the code.

  • Lines 2–3: The greet function takes three parameters: $name, $age, and $greeting. The $name and $age parameter is intended for the person’s name and age, respectively. The $greeting parameter has a default value of “Hello.’’ If a value is not provided when the function is called, it will use “Hello’’ as the default value. Inside the function, echo is used to output a message that combines the greeting, the person’s name, and their age.

  • Line 7: Here, we call the greet function with three arguments. The first argument, 25, corresponds to the $name parameter in the function. However, the order is incorrect. It should be the person’s name, not their age. The second argument, "Zack", corresponds to the $age parameter in the function. The third argument, "Hi", corresponds to the $greeting parameter in the function.

Code intricacies

There are a couple of intricacies in the coding example above:

Argument order mismatch

In the function call greet(25, "Zack", "Hi");, the order of arguments seems to be incorrect. The function is defined with the parameters. $name, $age, and $greeting, in that order. However, in the function call, the arguments are provided as 25, "Zack", "Hi". It’s typically expected to pass arguments in the order in which they are defined in the function signature. Here’s the corrected function call:

greet("Zack", 25, "Hi");

Default argument

The function greet has a default value for the third parameter, $greeting, set to “Hello.’’ If a value is not provided for $greeting in the function call, it will default to “Hello.’’ In the function call above, we provided a value for $greeting, but if you want to rely on the default value, you can also call the function like this:

greet("Zack", 25);

Using named arguments in PHP 8

Now, let’s modify our code and use the named arguments in the function call. To add named arguments, all we need to do is specify the parameter names along with their values when calling the function. For example, instead of just passing "Hi", "Zack", 25 as our input arguments, we’ll pass greeting: "Hi", name: "Zack", age: 25.

<?php
function greet($name, $age, $greeting = "Hello") {
    echo "$greeting, $name! You are $age years old.";
}
// Using named parameters in PHP 8
greet(greeting: "Hi", name: "Zack", age: 25 );
?>

In line 7, the function call still has an incorrect order of arguments, but the output will be Hi, Zack! You are 25 years old. which is the correct sentence that we expect from this function. So, if we use named arguments, no matter the order of arguments, our function will assign values to the input arguments correctly.

Conclusion

Named arguments in PHP 8 significantly improve how parameters are passed to functions, making the code more readable and maintainable. By specifying parameters by name, developers can avoid mistakes related to argument order and improve the clarity of function calls, especially when dealing with functions with numerous or optional parameters. This feature is a valuable addition to PHP, enhancing the overall developer experience and improving code quality.

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