Use PHP's ::class constant.

src/Bundle/Resources/contao/config/config.php

@@ -46,7 +46,7 @@ array_insert(
             ),
             'leaflet_about' => array
             (
-                'callback'   => 'Netzmacht\Contao\Leaflet\Backend\About',
+                'callback'   => Netzmacht\Contao\Leaflet\Backend\About::class,
                 'icon'       => 'bundles/netzmachtcontaoleaflet/img/about.png',
                 'stylesheet' => 'bundles/netzmachtcontaoleaflet/css/about.css',
             )

src/Bundle/Resources/contao/dca/tl_leaflet_vector.php

@@ -240,7 +240,7 @@ $GLOBALS['TL_DCA']['tl_leaflet_vector'] = [
             'label'            => &$GLOBALS['TL_LANG']['tl_leaflet_vector']['popup'],
             'exclude'          => true,
             'inputType'        => 'select',
-            'options_callback' => ['Netzmacht\Contao\Leaflet\Listener\Dca\MarkerDcaListener', 'getPopups'],
+            'options_callback' => ['netzmacht.contao_leaflet.listeners.dca.vector', 'getPopups'],
             'eval'             => [
                 'mandatory'          => false,
                 'tl_class'           => 'w50',

src/Listener/Dca/VectorDcaListener.php

@@ -13,6 +13,7 @@
 namespace Netzmacht\Contao\Leaflet\Listener\Dca;
 
 use Netzmacht\Contao\Leaflet\Model\IconModel;
+use Netzmacht\Contao\Leaflet\Model\PopupModel;
 use Netzmacht\Contao\Toolkit\Dca\Listener\AbstractListener;
 use Netzmacht\Contao\Toolkit\Dca\Manager;
 use Netzmacht\Contao\Toolkit\Dca\Options\OptionsBuilder;
@@ -107,4 +108,17 @@ class VectorDcaListener extends AbstractListener
 
         return $builder->getOptions();
     }
+
+    /**
+     * Get all popups.
+     *
+     * @return array
+     */
+    public function getPopups()
+    {
+        $collection = PopupModel::findAll(array('order' => 'title'));
+        $builder    = OptionsBuilder::fromCollection($collection, 'title');
+
+        return $builder->getOptions();
+    }
 }

src/Mapper/Control/AbstractControlMapper.php

@@ -13,6 +13,7 @@
 namespace Netzmacht\Contao\Leaflet\Mapper\Control;
 
 use Netzmacht\Contao\Leaflet\Mapper\AbstractTypeMapper;
+use Netzmacht\Contao\Leaflet\Model\ControlModel;
 
 /**
  * Class AbstractControlMapper is the base mapper for the control model.
@@ -26,7 +27,7 @@ class AbstractControlMapper extends AbstractTypeMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\ControlModel';
+    protected static $modelClass = ControlModel::class;
 
     /**
      * {@inheritdoc}

src/Mapper/Layer/AbstractLayerMapper.php

@@ -13,6 +13,7 @@
 namespace Netzmacht\Contao\Leaflet\Mapper\Layer;
 
 use Netzmacht\Contao\Leaflet\Mapper\AbstractTypeMapper;
+use Netzmacht\Contao\Leaflet\Model\LayerModel;
 
 /**
  * Class AbstractLayerMapper is the base mapper for the layer model.
@@ -26,7 +27,7 @@ class AbstractLayerMapper extends AbstractTypeMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\LayerModel';
+    protected static $modelClass = LayerModel::class;
 
     /**
      * {@inheritdoc}

src/Mapper/Layer/OverpassLayerMapper.php

@@ -39,7 +39,7 @@ class OverpassLayerMapper extends AbstractLayerMapper
      *
      * @var string
      */
-    protected static $definitionClass = 'Netzmacht\Contao\Leaflet\Definition\Layer\OverpassLayer';
+    protected static $definitionClass = OverpassLayer::class;
 
     /**
      * {@inheritdoc}

src/Mapper/MapMapper.php

@@ -33,7 +33,7 @@ class MapMapper extends AbstractMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\MapModel';
+    protected static $modelClass = MapModel::class;
 
     /**
      * Class of the definition being created.

src/Mapper/Style/AbstractStyleMapper.php

@@ -13,6 +13,7 @@
 namespace Netzmacht\Contao\Leaflet\Mapper\Style;
 
 use Netzmacht\Contao\Leaflet\Mapper\AbstractTypeMapper;
+use Netzmacht\Contao\Leaflet\Model\StyleModel;
 
 /**
  * Class AbstractStyleMapper is the base mapper for the style model.
@@ -26,5 +27,5 @@ abstract class AbstractStyleMapper extends AbstractTypeMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\StyleModel';
+    protected static $modelClass = StyleModel::class;
 }

src/Mapper/Style/FixedStyleMapper.php

@@ -12,6 +12,8 @@
 
 namespace Netzmacht\Contao\Leaflet\Mapper\Style;
 
+use Netzmacht\Contao\Leaflet\Definition\Style\FixedStyle;
+
 /**
  * Class FixedStyleMapper maps the fixed style to the corresponding definition.
  *
@@ -24,7 +26,7 @@ class FixedStyleMapper extends AbstractStyleMapper
      *
      * @var string
      */
-    protected static $definitionClass = 'Netzmacht\Contao\Leaflet\Definition\Style\FixedStyle';
+    protected static $definitionClass = FixedStyle::class;
 
     /**
      * Style type.

src/Mapper/Type/AbstractIconMapper.php

@@ -13,6 +13,7 @@
 namespace Netzmacht\Contao\Leaflet\Mapper\Type;
 
 use Netzmacht\Contao\Leaflet\Mapper\AbstractTypeMapper;
+use Netzmacht\Contao\Leaflet\Model\IconModel;
 
 /**
  * Class AbstractIconMapper is the base mapper for the icon model.
@@ -26,7 +27,7 @@ class AbstractIconMapper extends AbstractTypeMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\IconModel';
+    protected static $modelClass = IconModel::class;
 
     /**
      * {@inheritdoc}

src/Mapper/UI/MarkerMapper.php

@@ -17,6 +17,7 @@ use Netzmacht\Contao\Leaflet\Frontend\ValueFilter;
 use Netzmacht\Contao\Leaflet\Mapper\AbstractMapper;
 use Netzmacht\Contao\Leaflet\Mapper\DefinitionMapper;
 use Netzmacht\Contao\Leaflet\Model\IconModel;
+use Netzmacht\Contao\Leaflet\Model\MarkerModel;
 use Netzmacht\Contao\Leaflet\Model\PopupModel;
 use Netzmacht\Contao\Leaflet\Request\Request;
 use Netzmacht\LeafletPHP\Definition;
@@ -36,14 +37,14 @@ class MarkerMapper extends AbstractMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\MarkerModel';
+    protected static $modelClass = MarkerModel::class;
 
     /**
      * Class of the definition being created.
      *
      * @var string
      */
-    protected static $definitionClass = 'Netzmacht\LeafletPHP\Definition\UI\Marker';
+    protected static $definitionClass = Marker::class;
 
     /**
      * Frontend filter.

src/Mapper/UI/PopupMapper.php

@@ -32,14 +32,14 @@ class PopupMapper extends AbstractMapper
      *
      * @var string
      */
-    protected static $definitionClass = 'Netzmacht\LeafletPHP\Definition\UI\Popup';
+    protected static $definitionClass = Popup::class;
 
     /**
      * The model class.
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\PopupModel';
+    protected static $modelClass = PopupModel::class;
 
     /**
      * {@inheritdoc}

src/Mapper/Vector/AbstractVectorMapper.php

@@ -19,6 +19,7 @@ use Netzmacht\Contao\Leaflet\Mapper\AbstractTypeMapper;
 use Netzmacht\Contao\Leaflet\Mapper\DefinitionMapper;
 use Netzmacht\Contao\Leaflet\Model\PopupModel;
 use Netzmacht\Contao\Leaflet\Model\StyleModel;
+use Netzmacht\Contao\Leaflet\Model\VectorModel;
 use Netzmacht\Contao\Leaflet\Request\Request;
 use Netzmacht\LeafletPHP\Definition;
 use Netzmacht\LeafletPHP\Definition\HasPopup;
@@ -37,7 +38,7 @@ class AbstractVectorMapper extends AbstractTypeMapper
      *
      * @var string
      */
-    protected static $modelClass = 'Netzmacht\Contao\Leaflet\Model\VectorModel';
+    protected static $modelClass = VectorModel::class;
 
     /**
      * Frontend filter.