Refactor DatePicker instantiation in example

Moves DatePicker creation outside the button click handler to reuse the same instance. This simplifies the code and avoids creating a new DatePicker object on each click.

Author: InesaFitsner

sdk/python/examples/controls/date_picker/basic.py

@@ -14,20 +14,18 @@ def handle_dismissal(e: ft.Event[ft.DialogControl]):
 
     today = datetime.datetime.now()
 
+    d = ft.DatePicker(
+        first_date=datetime.datetime(year=today.year - 1, month=1, day=1),
+        last_date=datetime.datetime(year=today.year + 1, month=today.month, day=20),
+        on_change=handle_change,
+        on_dismiss=handle_dismissal,
+    )
+
     page.add(
         ft.Button(
             content="Pick date",
             icon=ft.Icons.CALENDAR_MONTH,
-            on_click=lambda e: page.show_dialog(
-                ft.DatePicker(
-                    first_date=datetime.datetime(year=today.year - 1, month=1, day=1),
-                    last_date=datetime.datetime(
-                        year=today.year + 1, month=today.month, day=20
-                    ),
-                    on_change=handle_change,
-                    on_dismiss=handle_dismissal,
-                )
-            ),
+            on_click=lambda e: page.show_dialog(d),
         )
     )