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Using Your Singleton

Getting the Instance​

Use the static getInstance() method to retrieve the singleton instance:

// Get the singleton instance
$example = Example::getInstance();

Instance Persistence​

The same instance is always returned, ensuring singleton behavior:

// Get the singleton instance
$example = Example::getInstance();

// Get another reference to the same instance
$anotherReference = Example::getInstance();

// Modify the property
$example->someProperty = "Changed value";

// This will output "Changed value" because both variables reference the same instance
echo $anotherReference->someProperty; // Output: Changed value

What You Cannot Do​

Cloning is Prohibited​

Attempting to clone a singleton instance will throw a SingletonException:

try {
    $cloned = clone $example;
} catch (\ByJG\DesignPattern\SingletonException $e) {
    echo "Cannot clone a singleton!";
}

Serialization is Prohibited​

Attempting to serialize a singleton will throw a SingletonException:

try {
    $serialized = serialize($example);
} catch (\ByJG\DesignPattern\SingletonException $e) {
    echo "Cannot serialize a singleton!";
}

Unserialization is Prohibited​

Attempting to unserialize a singleton will throw a SingletonException:

try {
    $unserialized = unserialize($someSerialized Data);
} catch (\ByJG\DesignPattern\SingletonException $e) {
    echo "Cannot deserialize a singleton!";
}

Best Practices​

Use for Shared State

Singletons are ideal for managing shared state or resources, such as:

  • Database connections
  • Configuration objects
  • Logging services
  • Cache managers
Thread Safety

This implementation is not thread-safe in multi-threaded environments. For such cases, consider using proper locking mechanisms.

Testing Considerations

Singletons can make unit testing more difficult because they maintain state across tests. Consider using dependency injection for better testability.

Next Steps​