docs(example): busy task

examples/09_advanced/busy-task.py

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+import time
+
+import trame.widgets.vuetify3 as v3
+from trame.app import get_server, asynchronous
+from trame.ui.vuetify3 import VAppLayout
+
+
+# -------------------------------------------------------------------
+# Helper
+# -------------------------------------------------------------------
+
+
+class AsyncTracker:
+    def __init__(self, server, name):
+        self.name = name
+        self.server = server
+        self.state = server.state
+
+    async def __aenter__(self):
+        with self.state:
+            self.state[self.name] = True
+        await self.server.network_completion
+
+    async def __aexit__(self, exc_t, exc_v, exc_tb):
+        with self.state:
+            self.state[self.name] = False
+        await self.server.network_completion
+
+
+# -------------------------------------------------------------------
+
+
+def long_task():
+    time.sleep(2)
+    print("Finished")
+
+
+async def run_long_task():
+    async with AsyncTracker(server, "loading"):
+        long_task()
+
+
+def run_task():
+    asynchronous.create_task(run_long_task())
+
+
+# -------------------------------------------------------------------
+
+server = get_server()
+state = server.state
+
+with VAppLayout(server) as layout:
+    with layout:
+        with v3.Template():
+            with v3.VOverlay(
+                v_model=("loading", False),
+                classes="align-center justify-center",
+                close_on_content_click=False,
+                persistent=True,
+                style="z-index: 10000;",
+            ):
+                v3.VProgressCircular(color="primary", size=64, indeterminate=True)
+        v3.VBtn("Long task (no tracking)", click=long_task)
+        v3.VBtn("Long task (tracking)", click=run_task)
+
+
+if __name__ == "__main__":
+    server.start()