Refactor demo app to consolidate logic into main method

CLAUDE.md

@@ -32,6 +32,7 @@ All serialized files (`.abap`, `.xml`, and any other abapGit-managed file types)
 - Follow the [SAP ABAP Style Guide](https://github.com/SAP/styleguides/blob/main/clean-abap/CleanABAP.md).
 - Never use an init flag attribute (`check_initialized`, `mv_init`, `is_initialized`, etc.). Always use `client->check_on_init( )` instead.
 - Use backticks for all string literals, not single quotes.
+- Prefer functional to procedural language constructs — use `var = VALUE #( ).` to reset a variable, never `CLEAR var.`.
 - Do not use Hungarian notation — no type prefixes on variable or attribute names (e.g. `product` not `lv_product`, `client` not `mo_client`).
 - Class names are always written in **lowercase** in both `DEFINITION` and `IMPLEMENTATION` — never uppercase.
 - Classes are **not** `FINAL` — do not add the `FINAL` keyword to class definitions.
@@ -263,6 +264,8 @@ Key rules for `z2ui5_cl_util_xml`:
 
 Write everything directly in `main` — no method encapsulation needed. Count only the lines inside the `main` method, not the total class length.
 
+**Do not extract `view_display` or any other helper method just because the app has a view.** A separate `view_display` method is only justified when the app is large enough to warrant the full canonical structure (≥ 50 lines in `main`). Extracting it in a simple app adds unnecessary indirection.
+
 ### Larger apps — canonical template
 
 The following is the **maximum structure**. Only add methods that are actually needed.

src/z2ui5_cl_demo_app_001.clas.abap

@@ -1,84 +1,50 @@
-CLASS z2ui5_cl_demo_app_001 DEFINITION PUBLIC CREATE PUBLIC.
+CLASS z2ui5_cl_demo_app_001 DEFINITION PUBLIC.
 
   PUBLIC SECTION.
-
     INTERFACES z2ui5_if_app.
 
     DATA product  TYPE string.
     DATA quantity TYPE string.
 
-
   PROTECTED SECTION.
-
-    DATA client TYPE REF TO z2ui5_if_client.
-
-    METHODS z2ui5_set_data.
-
-    METHODS display_view
-      IMPORTING
-        client TYPE REF TO z2ui5_if_client.
-    METHODS on_event
-      IMPORTING
-        client TYPE REF TO z2ui5_if_client.
-
   PRIVATE SECTION.
 ENDCLASS.
 
 
-
 CLASS z2ui5_cl_demo_app_001 IMPLEMENTATION.
 
   METHOD z2ui5_if_app~main.
 
-    me->client = client.
-
-
     IF client->check_on_init( ).
-      display_view( client ).
-      z2ui5_set_data( ).
-    ENDIF.
-
-    on_event( client ).
-
-  ENDMETHOD.
-
-
-  METHOD display_view.
-
-    DATA(view) = z2ui5_cl_xml_view=>factory( ).
-    client->view_display( view->shell(
-           )->page(
-                   title          = 'abap2UI5 - First Example'
-                   navbuttonpress = client->_event_nav_app_leave( )
-                   shownavbutton  = client->check_app_prev_stack( )
-        )->simple_form( title = 'Form Title' editable = abap_true
-                   )->content( 'form'
-                       )->title( 'Input'
-                       )->label( 'quantity'
-                       )->input( client->_bind_edit( quantity )
-                       )->label( `product`
-                       )->input( value = product enabled = abap_false
-                       )->button(
-                           text  = 'post'
-                           press = client->_event( 'BUTTON_POST' )
-            )->stringify( ) ).
-
-  ENDMETHOD.
 
-
-  METHOD on_event.
-
-    IF client->check_on_event( 'BUTTON_POST' ).
+      product  = `products`.
+      quantity = `500`.
+
+      DATA(view) = z2ui5_cl_xml_view=>factory( ).
+      view->shell(
+          )->page(
+              title          = `abap2UI5 - First Example`
+              navbuttonpress = client->_event_nav_app_leave( )
+              shownavbutton  = client->check_app_prev_stack( )
+              )->simple_form(
+                  title    = `Form Title`
+                  editable = abap_true
+                  )->content( `form`
+                  )->label( `quantity`
+                  )->input( client->_bind_edit( quantity )
+                  )->label( `product`
+                  )->input(
+                      value   = product
+                      enabled = abap_false
+                  )->button(
+                      text  = `post`
+                      press = client->_event( `BUTTON_POST` ) ).
+      client->view_display( view->stringify( ) ).
+
+    ELSEIF client->check_on_event( `BUTTON_POST` ).
       client->message_toast_display( |{ product } { quantity } - send to the server| ).
     ENDIF.
 
   ENDMETHOD.
 
-
-  METHOD z2ui5_set_data.
-
-    product  = 'products'.
-    quantity = '500'.
-
-  ENDMETHOD.
 ENDCLASS.