callbacks: global_state: save data vector to ron file on disk

* new functionality
* save imported / edited data-structures persitantliy
  on disk to file in 'ron' format

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

advotracker/src/callbacks/global_state.rs

@@ -8,10 +8,10 @@
 use orbtk::prelude::*;
 
 //use crate::data::keys;
-// use crate::{
-//     //data::structures::PolicyList,
-//     data::keys::*
-// };
+use crate::{
+     data::structures::PolicyList,
+     data::keys::*
+};
 
 /// Provides generic methods to handle states of datatypes (e.g. used in `PolicyList`).
 pub trait GlobalState {
@@ -41,14 +41,19 @@ pub trait GlobalState {
         Some(copy)
     }
 
-    // Save the data.
-    // fn save(&self, registry: &mut Registry, ctx: &mut Context) {
-    //     registry
-    //         .get::<Settings>("settings")
-    //         .save(
-    //             PROP_POLICY_LIST,
-    //             ctx.widget().get::<PolicyList>(PROP_POLICY_LIST),
-    //         )
-    //         .unwrap();
-    // }
+    /// Save the our data structure and convert it to `ron` file format.
+    /// The cargo package identifier (here: 'nwx.advotracker') is taken to create the app directory.
+    /// in users 'settings directory'. The directory location is OS dependant
+    /// (Windows: AppData, Unix: XDG_CONFIG_HOME, MacOS: $HOME/Library/Preferences).
+    /// The data is stored in filename PROP_ADVOTRACKER (here: `advotracker.ron`)
+
+    fn save(&self, registry: &mut Registry, ctx: &mut Context<'_>) {
+        registry
+            .get::<Settings>("settings")
+            .save(
+                PROP_ADVOTRACKER,
+                ctx.widget().get::<PolicyList>(PROP_ADVOTRACKER),
+            )
+            .unwrap();
+    }
 }