Comma at the end of function arguments in PHP (trailing comma)

Have you ever added a new argument to a function or constructor in PHP and forgotten to add a comma at the end of the previous line? It’s a common mistake that can lead to unnecessary fixes and frustration.

Fortunately, since PHP 7.3 you can use the so-called trailing comma, i.e., a comma after the last argument in function calls, function declarations, and arrays. Thanks to this, when you add a new argument, you don’t have to remember to manually add a comma at the end of the previous line.

🛑 Example without trailing comma

class User {
    public function __construct(
        string $name,
        int $age
    ) {
        // ...
    }
}

If you want to add another argument, you have to go back to the previous line and add a comma:

class User {
    public function __construct(
        string $name,
        int $age, // you have to add a comma
        string $email
    ) {
        // ...
    }
}

✅ Example with trailing comma

class User {
    public function __construct(
        string $name,
        int $age,
    ) {
        // ...
    }
}

Now you can simply add another argument without worrying about commas:

class User {
    public function __construct(
        string $name,
        int $age,
        string $email,
    ) {
        // ...
    }
}

📅 Since when?

Trailing comma in function and method argument lists is available since PHP 7.3. Previously, it was only available in arrays.

📝 Summary

Using the trailing comma:

• makes adding and removing arguments easier,
• reduces the risk of syntax errors,
• improves code readability in the long run.

It’s worth using this feature, especially in larger projects!