Assigning new by Reference

Also Known As

TL;DR

Explanation

In PHP 4, objects were copied by value — $obj = new Foo() created a value copy on assignment. PHP 5 changed objects to pass-by-handle (similar to references): assigning an object variable gives a new variable pointing to the same object, not a copy. Therefore $obj = &new Foo() is redundant — the & is a no-op. Worse, in PHP 7+ it generates an E_DEPRECATED warning. The pattern is purely a legacy PHP 4 pattern that has no purpose in modern code.

Common Misconception

Why It Matters

Common Mistakes

• $this->property = &new ClassName() — redundant & on object assignment.
• $obj = &new PDO(...) — object is already passed by handle.
• Confusing object references (all objects) with variable references (&$var).
• Not recognising this as a PHP 4 legacy pattern requiring modernisation.

Code Examples

// PHP 4 legacy — redundant & operator:
$db      = &new PDO('mysql:host=localhost', 'root', 'pass');
$service = &new UserService($db);
$this->repo = &new UserRepository();

// Generates: E_DEPRECATED in PHP 7
// No effect in PHP 5+ — objects are always by handle

// Modern PHP — no & needed:
$db      = new PDO('mysql:host=localhost', 'root', 'pass');
$service = new UserService($db);
$this->repo = new UserRepository();

// If you genuinely need two variables to reference the same assignment:
$a = new Foo();
$b = &$a; // Reference the variable, not the construction

References

• ↗ https://www.php.net/manual/en/language.oop5.references.php

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