API Add object:children command to list concrete extensions of a class

console.yml

@@ -11,5 +11,6 @@ Commands:
   - SilverLeague\Console\Command\Member\ChangeGroupsCommand
   - SilverLeague\Console\Command\Member\ChangePasswordCommand
   - SilverLeague\Console\Command\Member\CreateCommand
+  - SilverLeague\Console\Command\Object\ChildrenCommand
   - SilverLeague\Console\Command\Object\ExtensionsCommand
   - SilverLeague\Console\Command\Object\LookupCommand

src/Command/Object/ChildrenCommand.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace SilverLeague\Console\Command\Object;
+
+use SilverLeague\Console\Command\SilverStripeCommand;
+use SilverStripe\Core\ClassInfo;
+use Symfony\Component\Console\Helper\Table;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * List all child classes of a given class name
+ *
+ * @package silverstripe-console
+ * @author  Robbie Averill <robbie@averill.co.nz>
+ */
+class ChildrenCommand extends SilverStripeCommand
+{
+    /**
+     * {@inheritDoc}
+     */
+    protected function configure()
+    {
+        $this
+            ->setName('object:children')
+            ->setDescription('List all child classes of a given class, e.g. "Page"')
+            ->addArgument('object', InputArgument::REQUIRED, 'The class to find children for');
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $object = $input->getArgument('object');
+        $classes = (array) ClassInfo::subclassesFor($object);
+        // Remove the class itself
+        array_shift($classes);
+        if (!$classes) {
+            $output->writeln('There are no child classes for ' . $object);
+            return;
+        }
+        sort($classes);
+        $rows = array_map(function ($class) {
+            return [$class];
+        }, $classes);
+
+        $output->writeln('<info>Child classes for ' . $object . ':</info>');
+        $table = new Table($output);
+        $table
+            ->setHeaders(['Class name'])
+            ->setRows($rows)
+            ->render();
+    }
+}

src/Command/Object/ExtensionsCommand.php

@@ -4,6 +4,7 @@
 
 use SilverLeague\Console\Command\SilverStripeCommand;
 use SilverStripe\Core\Config\Config;
+use SilverStripe\Core\Object;
 use Symfony\Component\Console\Helper\Table;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
@@ -25,7 +26,7 @@ protected function configure()
         $this
             ->setName('object:extensions')
             ->setDescription('List all Extensions of a given Object, e.g. "Page"')
-            ->addArgument('object', InputArgument::REQUIRED, 'The Object to look up');
+            ->addArgument('object', InputArgument::REQUIRED, 'The Object to find Extensions for');
     }
 
     /**
@@ -34,14 +35,15 @@ protected function configure()
     protected function execute(InputInterface $input, OutputInterface $output)
     {
         $object = $input->getArgument('object');
-        $extensions = \SilverStripe\Core\Object::get_extensions($object);
+        $extensions = Object::get_extensions($object);
         if (!$extensions) {
             $output->writeln('There are no Extensions registered for ' . $object);
             return;
         }
         sort($extensions);
 
-        $isCmsClass = singleton($object) instanceof \SilverStripe\CMS\Model\SiteTree;
+        $isCmsClass = (class_exists('SilverStripe\\CMS\\Model\\SiteTree')
+            && singleton($object) instanceof \SilverStripe\CMS\Model\SiteTree);
 
         $output->writeln('<info>Extensions for ' . $object . ':</info>');
         $table = new Table($output);