MAGETWO-54205: After Disable/Enable Magento modules via CLI all cache types become disabled

- minor update based on review

Author: ark99

src/MagentoHackathon/Composer/Magento/Plugin.php

@@ -129,12 +129,7 @@ public function onPackageUnistall(\Composer\Installer\PackageEvent $event)
         $deployStrategy = $this->installer->getDeployStrategy($package);
         $deployStrategy->rmdirRecursive($packageInstallationPath . $ds . $libPath);
         $deployStrategy->rmdirRecursive($packageInstallationPath . $ds . $magentoPackagePath);
-
-        // Force regeneration of var/di, var/cache, var/generation on next object manager invocation
-        if (file_exists($this->installer->getTargetDir() . $this->varFolder)) {
-            $filename = $this->installer->getTargetDir() . $this->varFolder . $this->regenerate;
-            touch($filename);
-        }
+        $this->requestRegeneration();
     }
 
     /**
@@ -161,12 +156,7 @@ public function onNewCodeEvent(\Composer\Script\Event $event)
         $this->deployManager->doDeploy();
         $this->deployLibraries();
         $this->saveVendorDirPath($event->getComposer());
-
-        // Force regeneration of var/di, var/cache, var/generation on next object manager invocation
-        if (file_exists($this->installer->getTargetDir() . $this->varFolder)) {
-            $filename = $this->installer->getTargetDir() . $this->varFolder . $this->regenerate;
-            touch($filename);
-        }
+        $this->requestRegeneration();
     }
 
 
@@ -289,4 +279,17 @@ private function saveVendorDirPath(Composer $composer)
 AUTOLOAD;
         file_put_contents($vendorPathFile, $content);
     }
+
+    /**
+     * Force regeneration of var/di, var/cache, var/generation on next object manager invocation
+     *
+     * @return void
+     */
+    private function requestRegeneration()
+    {
+        if (is_writable($this->installer->getTargetDir() . $this->varFolder)) {
+            $filename = $this->installer->getTargetDir() . $this->varFolder . $this->regenerate;
+            touch($filename);
+        }
+    }
 }