1.2.63. Avoid Optional Properties¶
Avoid optional properties, to prevent littering the code with existence checks.
When a property has to be checked once for existence, it is safer to check it each time. This leads to a decrease in readability and a lot of checks added to the code.
Either make sure the property is set with an actual object rather than with null, or use a null object. A null object offers the same interface than the expected object, but does nothing. It allows calling its methods, without running into a Fatal error, nor testing it.
<?php
// Example is courtesy 'The Coding Machine' : it has been adapted from its original form. See link below.
class MyMailer {
private $logger;
public function __construct(LoggerInterface $logger = null) {
$this->logger = $logger;
}
private function sendMail(Mail $mail) {
// Since $this->logger may be null, it must be tested anytime it is used.
if ($this->logger) {
$this->logger->info('Mail successfully sent.');
}
}
}
?>
See also Avoid optional services as much as possible, The Null Object Pattern – Polymorphism in Domain Models and Practical PHP Refactoring: Introduce Null Object.
1.2.63.1. Suggestions¶
Use a null object to fill any missing value
Make sure the property is set at constructor time
1.2.63.2. Specs¶
Short name |
Classes/AvoidOptionalProperties |
Rulesets |
|
Exakat since |
0.12.0 |
PHP Version |
All |
Severity |
Major |
Time To Fix |
Slow (1 hour) |
Precision |
Very high |
Features |
property, null |
Examples |
|
Available in |