PHP Property Hooks
last modified February 15, 2025
In this article, we show how to use property hooks in PHP 8.4.
Property hooks are a new feature that allows developers to define custom
behavior for property access and modification. This feature provides greater
control over how properties are read and written, enabling more robust and
maintainable code.
Property hooks are particularly useful for enforcing validation, logging, or other custom logic when accessing or modifying properties.
Main Features of PHP Property Hooks
- Custom Getter Logic: Define custom behavior when reading a property.
- Custom Setter Logic: Define custom behavior when writing to a property.
- Validation: Enforce validation rules when setting property values.
- Logging: Log property access or modification for debugging or auditing purposes.
- Encapsulation: Encapsulate property access logic within the class, improving code organization.
Basic Usage of Property Hooks
The following example demonstrates how to define and use property hooks in PHP 8.4.
<?php
class Product
{
private string $name;
// Property hook for getting the name
public function __get(string $property): mixed
{
return match ($property) {
'name' => strtoupper($this->name),
default => null,
};
}
// Property hook for setting the name
public function __set(string $property, mixed $value): void
{
match ($property) {
'name' => $this->setName($value),
default => null,
};
}
private function setName(string $value): void
{
if (strlen($value) < 3) {
throw new Exception("Name must be at least 3 characters long.");
}
$this->name = $value;
}
}
$product = new Product();
$product->name = "Laptop"; // Set the name
echo $product->name; // Get the name (outputs in uppercase)
In this program, the __get and __set methods are used
to define custom behavior for accessing and modifying the name
property. The __get method converts the name to uppercase when
accessed, and the __set method enforces a minimum length
requirement.
$ php main.php LAPTOP
Validation with Property Hooks
The following example demonstrates how to use property hooks to enforce validation rules when setting property values.
<?php
class User
{
private int $age;
// Property hook for setting the age
public function __set(string $property, mixed $value): void
{
match ($property) {
'age' => $this->setAge($value),
default => null,
};
}
// Property hook for getting the age
public function __get(string $property): mixed
{
return match ($property) {
'age' => $this->age,
default => null,
};
}
private function setAge(int $value): void
{
if ($value < 0 || $value > 120) {
throw new Exception("Age must be between 0 and 120.");
}
$this->age = $value;
}
}
$user = new User();
$user->age = 25; // Valid age
echo $user->age; // Outputs: 25
// $user->age = 150; // Throws an exception
In this program, the __set method enforces a validation rule for the age property, ensuring that the value is between 0 and 120. The __get method allows reading the age property.
$ php main.php 25
Logging with Property Hooks
The following example demonstrates how to use property hooks to log property access and modification.
<?php
class Account
{
private float $balance = 0.0;
// Property hook for getting the balance
public function __get(string $property): mixed
{
return match ($property) {
'balance' => $this->getBalance(),
default => null,
};
}
// Property hook for setting the balance
public function __set(string $property, mixed $value): void
{
match ($property) {
'balance' => $this->setBalance($value),
default => null,
};
}
private function getBalance(): float
{
echo "Balance accessed: {$this->balance}\n";
return $this->balance;
}
private function setBalance(float $value): void
{
echo "Balance updated from {$this->balance} to $value\n";
$this->balance = $value;
}
}
$account = new Account();
$account->balance = 100.0; // Logs: Balance updated from 0 to 100
echo $account->balance; // Logs: Balance accessed: 100
In this program, the __get and __set methods log
access and modification of the balance property. This is useful for
debugging or auditing purposes.
$ php main.php Balance updated from 0 to 100 Balance accessed: 100 100
Source
PHP Property Hooks - Documentation
In this article, we have shown how to use property hooks in PHP 8.4 to define custom behavior for property access and modification. Property hooks are a powerful tool for enforcing validation, logging, and encapsulating property logic.
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