Migrating to Hooks

Migrating to Hooks

Migrating Getters and Setters to Property Hooks

Getter and setter pairs existed so that a rule could be added later without changing callers. Hooks give public properties that option. Migrate in three steps: make the property public and move the setter's rule into a set hook; turn computed getters into virtual get hooks; keep the old methods as thin wrappers marked #[\Deprecated] (Subsection 4.11.14) until their callers are gone.

A Customer whose email rule moved from a setter into a set hookPHP

<?php
final class Customer {
  public string $email = '' {
    set => strtolower(filter_var($value, FILTER_VALIDATE_EMAIL)
      ?: throw new InvalidArgumentException("Invalid email: $value"));
  }
  #[\Deprecated('use the $email property', since: '2.0')]
  public function getEmail(): string { return $this->email; }     // kept for old callers
}
$c = new Customer();
$c->email = 'Ann@Example.COM';
$viaGetter = $c->getEmail();                                       // old call site still works
echo $c->email, ' ', $viaGetter, "\n";
try { $c->email = 'nope'; }
catch (InvalidArgumentException $e) { echo $e->getMessage(), "\n"; }

Output

PHP Deprecated:  Method Customer::getEmail() is deprecated since 2.0, use the $email property
  in /tmp/ch04-11/migrate.php on line 12
ann@example.com ann@example.com
Invalid email: nope

A setter that exists only to block outside writes becomes private(set) (Subsection 4.11.10). Keep as methods any setter that logs, dispatches events or calls other objects.

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