ADD examples of Friend with inheritance

examples/friend/friendWIthInheritance.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FriendWithInheritance;
+
+use DaveLiddament\PhpLanguageExtensions\Friend;
+
+
+interface Emailer
+{
+    #[Friend(EmailQueueProcessor::class)]
+    public function sendEmail(): void;
+}
+
+class PhpMailer implements Emailer
+{
+    public function sendEmail(): void
+    {
+    }
+}
+
+
+class EmailQueueProcessor
+{
+    public function sendEmail(): void
+    {
+        $mailer = new PhpMailer();
+        $mailer->sendEmail(); // OK
+    }
+}
+
+class AnotherClass {
+    public function sendEmail(): void
+    {
+        $mailer = new PhpMailer();
+        $mailer->sendEmail(); // ERROR
+    }
+}
+
+

examples/friend/friendWIthInheritance2.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FriendWithInheritance2;
+
+use DaveLiddament\PhpLanguageExtensions\Friend;
+
+
+interface Command
+{
+    #[Friend(CommandProcessor::class)]
+    public function execute(): void;
+}
+
+class PrintCommand implements Command
+{
+
+    public function execute(): void
+    {
+    }
+}
+
+
+interface CommandProcessor
+{
+    public function process(Command $command);
+}
+
+class PrintCommandProcessor implements CommandProcessor
+{
+    public function process(Command $command): void
+    {
+        $command->execute(); // OK
+    }
+}
+
+
+class AnotherClass
+{
+    public function process(Command $command):  void
+    {
+        $command->execute(); // ERROR
+    }
+}