classImplements.class - Phpstan

Code example

php

<?php declare(strict_types = 1);

class Logger
{
}

class FileLogger implements Logger
{
}

Why is it reported?

In PHP, a class can only implement interfaces. The implements keyword is reserved exclusively for interface types. Using a class in the implements clause is not valid.

In the example above, FileLogger attempts to implement Logger, which is a class, not an interface.

How to fix it

Extract an interface from the class, then implement the interface:

diff-php

 <?php declare(strict_types = 1);

-class Logger
+interface LoggerInterface
 {
+	public function log(string $message): void;
 }

-class FileLogger implements Logger
+class FileLogger implements LoggerInterface
 {
+	public function log(string $message): void
+	{
+		file_put_contents('app.log', $message . PHP_EOL, FILE_APPEND);
+	}
 }

Alternatively, if the intent is to reuse functionality from the parent class, use extends instead of implements:

diff-php

 <?php declare(strict_types = 1);

-class FileLogger implements Logger
+class FileLogger extends Logger
 {
 }