introducing the SubAction component in Porto.

Tried to avoid that for long time, but seems now way to avoid it.
In some situations, where you have large Actions, you need to share some
sequence of Tasks (not only tasks) to avoid duplicate code between
both actions, they should be able to call SubAction

app/Ship/Parents/Actions/Action.php

@@ -11,11 +11,13 @@
  */
 abstract class Action
 {
-
     use CallableTrait;
 
     /**
-     * @var
+     * Set automatically by the controller after calling an Action.
+     * Allows the Action to know which UI invoke it, to modify it's behaviour based on it, when needed.
+     *
+     * @var string
      */
     protected $ui;
 

app/Ship/Parents/Actions/SubAction.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Ship\Parents\Actions;
+
+/**
+ * Class Action.
+ *
+ * @author  Mahmoud Zalt <[email protected]>
+ */
+abstract class SubAction extends Action
+{
+
+}

docs/_docs/D.components/subactions.md

@@ -0,0 +1,55 @@
+---
+title: "Sub Actions"
+category: "Components"
+order: 5
+---
+
+### Definition & Principles
+
+Read from the [**Porto SAP Documentation (#SubActions)**](https://github.com/Mahmoudz/Porto#SubActions).
+
+### Rules
+
+- All SubActions MUST extend from `App\Ship\Parents\Actions\SubAction`.
+
+### Folder Structure
+
+```
+ - app
+    - Containers
+        - {container-name}
+            - Actions
+                - ValidateAddressSubAction.php
+                - BuildOrderSubAction.php
+                - ...
+```
+
+### Code Sample
+
+**ValidateAddressSubAction User Action:**
+
+```php
+<?php
+
+namespace App\Containers\Shipment\Actions;
+
+use App\Containers\Recipient\Models\Recipient;
+use App\Containers\Recipient\Tasks\UpdateRecipientTask;
+use App\Containers\Shipment\Tasks\ValidateAddressWithEasyPostTask;
+use App\Containers\Shipment\Tasks\ValidateAddressWithMelissaDataTask;
+use App\Ship\Parents\Actions\SubAction;
+
+class ValidateAddressSubAction extends SubAction
+{
+    public function run(Recipient $recipient)
+    {
+        $hasValidAddress = true;
+
+        $easyPostResponse = $this->call(ValidateAddressWithEasyPostTask::class, [$recipient]);
+
+        ...
+    }
+}
+```
+
+**Every feature available for Actions, is also available in SubActions.**