Drop Python 3.6.

Use `asyncio.get_running_loop()` and `asyncio.run()`. Stop using
`asyncio.get_event_loop()` and `asyncio.set_event_loop()`.

Author: jonathanslenders

examples/ssh/asyncssh-server.py

@@ -4,13 +4,13 @@
 """
 import asyncio
 import logging
+from asyncio import run
 
 import asyncssh
 from pygments.lexers.html import HtmlLexer
 
 from prompt_toolkit.completion import WordCompleter
 from prompt_toolkit.contrib.ssh import PromptToolkitSSHServer, PromptToolkitSSHSession
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.lexers import PygmentsLexer
 from prompt_toolkit.shortcuts import ProgressBar, print_formatted_text
 from prompt_toolkit.shortcuts.dialogs import input_dialog, yes_no_dialog
@@ -101,22 +101,21 @@ async def interact(ssh_session: PromptToolkitSSHSession) -> None:
     await input_dialog("Input dialog", "Running over asyncssh").run_async()
 
 
-def main(port=8222):
+async def main(port=8222):
     # Set up logging.
     logging.basicConfig()
     logging.getLogger().setLevel(logging.DEBUG)
 
-    loop = get_event_loop()
-    loop.run_until_complete(
-        asyncssh.create_server(
-            lambda: PromptToolkitSSHServer(interact),
-            "",
-            port,
-            server_host_keys=["/etc/ssh/ssh_host_ecdsa_key"],
-        )
+    await asyncssh.create_server(
+        lambda: PromptToolkitSSHServer(interact),
+        "",
+        port,
+        server_host_keys=["/etc/ssh/ssh_host_ecdsa_key"],
     )
-    loop.run_forever()
+
+    # Run forever.
+    await asyncio.Future()
 
 
 if __name__ == "__main__":
-    main()
+    asyncio.run(main())

examples/telnet/chat-app.py

@@ -6,9 +6,9 @@
 """
 import logging
 import random
+from asyncio import Future, run
 
 from prompt_toolkit.contrib.telnet.server import TelnetServer
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.formatted_text import HTML
 from prompt_toolkit.shortcuts import PromptSession, clear
 
@@ -91,11 +91,13 @@ def _send_to_everyone(sender_connection, name, message, color):
             )
 
 
-def main():
+async def main():
     server = TelnetServer(interact=interact, port=2323)
     server.start()
-    get_event_loop().run_forever()
+
+    # Run forever.
+    await Future()
 
 
 if __name__ == "__main__":
-    main()
+    run(main())

examples/telnet/dialog.py

@@ -3,9 +3,9 @@
 Example of a telnet application that displays a dialog window.
 """
 import logging
+from asyncio import Future, run
 
 from prompt_toolkit.contrib.telnet.server import TelnetServer
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.shortcuts.dialogs import yes_no_dialog
 
 # Set up logging
@@ -22,11 +22,13 @@ async def interact(connection):
     connection.send("Bye.\n")
 
 
-def main():
+async def main():
     server = TelnetServer(interact=interact, port=2323)
     server.start()
-    get_event_loop().run_forever()
+
+    # Run forever.
+    await Future()
 
 
 if __name__ == "__main__":
-    main()
+    run(main())

examples/telnet/hello-world.py

@@ -7,9 +7,9 @@
 That is probably the preferred way if you only need Python 3 support.
 """
 import logging
+from asyncio import Future, run
 
 from prompt_toolkit.contrib.telnet.server import TelnetServer
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.shortcuts import PromptSession, clear
 
 # Set up logging
@@ -30,11 +30,13 @@ async def interact(connection):
     connection.send("Bye.\n")
 
 
-def main():
+async def main():
     server = TelnetServer(interact=interact, port=2323)
     server.start()
-    get_event_loop().run_forever()
+
+    # Run forever.
+    await Future()
 
 
 if __name__ == "__main__":
-    main()
+    run(main())

examples/telnet/toolbar.py

@@ -4,10 +4,10 @@
 in the prompt.
 """
 import logging
+from asyncio import Future, run
 
 from prompt_toolkit.completion import WordCompleter
 from prompt_toolkit.contrib.telnet.server import TelnetServer
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.shortcuts import PromptSession
 
 # Set up logging
@@ -35,11 +35,13 @@ def get_toolbar():
     connection.send("Bye.\n")
 
 
-def main():
+async def main():
     server = TelnetServer(interact=interact, port=2323)
     server.start()
-    get_event_loop().run_forever()
+
+    # Run forever.
+    await Future()
 
 
 if __name__ == "__main__":
-    main()
+    run(main())

setup.py

@@ -30,26 +30,16 @@ def get_version(package):
     package_dir={"": "src"},
     package_data={"prompt_toolkit": ["py.typed"]},
     install_requires=["wcwidth"],
-    # We require Python 3.6.2 for three reasons:
-    # - Syntax for variable annotations - PEP 526.
-    # - Asynchronous generators - PEP 525.
-    # - New type annotations in 3.6.2 (i.e. NoReturn)
-    # Also, 3.6.0 doesn't have `typing.AsyncGenerator` yet. 3.6.1 does.
-    # Python 3.7 is suggested, because:
+    # We require Python 3.7, because we need:
     # - Context variables - PEP 567
-    # (The current application is derived from a context variable.)
-    # There is no intension to support Python 3.5, because prompt_toolkit 2.0
-    # does run fine on any older Python version starting from Python 2.6, and
-    # it is possible to write code that runs both against prompt_toolkit
-    # version 2 and 3.
-    python_requires=">=3.6.2",
+    # - `asyncio.run()`
+    python_requires=">=3.7.0",
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Intended Audience :: Developers",
         "License :: OSI Approved :: BSD License",
         "Operating System :: OS Independent",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",

src/prompt_toolkit/application/application.py

@@ -10,8 +10,7 @@
     Future,
     Task,
     ensure_future,
-    new_event_loop,
-    set_event_loop,
+    get_running_loop,
     sleep,
 )
 from contextlib import ExitStack, contextmanager
@@ -49,7 +48,7 @@
     get_traceback_from_context,
     run_in_executor_with_context,
 )
-from prompt_toolkit.eventloop.utils import call_soon_threadsafe, get_event_loop
+from prompt_toolkit.eventloop.utils import call_soon_threadsafe
 from prompt_toolkit.filters import Condition, Filter, FilterOrBool, to_filter
 from prompt_toolkit.formatted_text import AnyFormattedText
 from prompt_toolkit.input.base import Input
@@ -458,7 +457,7 @@ def invalidate(self) -> None:
         """
         if not self._is_running:
             # Don't schedule a redraw if we're not running.
-            # Otherwise, `get_event_loop()` in `call_soon_threadsafe` can fail.
+            # Otherwise, `get_running_loop()` in `call_soon_threadsafe` can fail.
             # See: https://github.com/dbcli/mycli/issues/797
             return
 
@@ -787,7 +786,7 @@ def flush_input() -> None:
 
         @contextmanager
         def get_loop() -> Iterator[AbstractEventLoop]:
-            loop = get_event_loop()
+            loop = get_running_loop()
             self.loop = loop
 
             try:
@@ -941,14 +940,6 @@ def run_in_thread() -> None:
                     )
                 except BaseException as e:
                     exception = e
-                finally:
-                    # Make sure to close the event loop in this thread. Running
-                    # the application creates a new loop (because we're in
-                    # another thread), but it doesn't get closed automatically
-                    # (also not by the garbage collector).
-                    loop = get_event_loop()
-                    loop.run_until_complete(loop.shutdown_asyncgens())
-                    loop.close()
 
             thread = threading.Thread(target=run_in_thread)
             thread.start()
@@ -958,21 +949,7 @@ def run_in_thread() -> None:
                 raise exception
             return result
 
-        # We don't create a new event loop by default, because we want to be
-        # sure that when this is called multiple times, each call of `run()`
-        # goes through the same event loop. This way, users can schedule
-        # background-tasks that keep running across multiple prompts.
-        try:
-            loop = get_event_loop()
-        except RuntimeError:
-            # Possibly we are not running in the main thread, where no event
-            # loop is set by default. Or somebody called `asyncio.run()`
-            # before, which closes the existing event loop. We can create a new
-            # loop.
-            loop = new_event_loop()
-            set_event_loop(loop)
-
-        return loop.run_until_complete(
+        return asyncio.run(
             self.run_async(
                 pre_run=pre_run,
                 set_exception_handler=set_exception_handler,
@@ -1074,7 +1051,7 @@ def create_background_task(
 
         This is not threadsafe.
         """
-        loop = self.loop or get_event_loop()
+        loop = self.loop or get_running_loop()
         task: asyncio.Task[None] = loop.create_task(coroutine)
         self._background_tasks.add(task)
 
@@ -1093,7 +1070,7 @@ def _on_background_task_done(self, task: "asyncio.Task[None]") -> None:
 
         exc = task.exception()
         if exc is not None:
-            get_event_loop().call_exception_handler(
+            get_running_loop().call_exception_handler(
                 {
                     "message": f"prompt_toolkit.Application background task {task!r} "
                     "raised an unexpected exception.",
@@ -1501,7 +1478,7 @@ def attach_winch_signal_handler(
 
     # Keep track of the previous handler.
     # (Only UnixSelectorEventloop has `_signal_handlers`.)
-    loop = get_event_loop()
+    loop = get_running_loop()
     previous_winch_handler = getattr(loop, "_signal_handlers", {}).get(sigwinch)
 
     try:

src/prompt_toolkit/completion/base.py

@@ -267,7 +267,7 @@ async def get_completions_async(
         # def get_all_in_thread() -> List[Completion]:
         #   return list(self.get_completions(document, complete_event))
 
-        # completions = await get_event_loop().run_in_executor(None, get_all_in_thread)
+        # completions = await get_running_loop().run_in_executor(None, get_all_in_thread)
         # for completion in completions:
         #   yield completion
 

src/prompt_toolkit/contrib/ssh/server.py

@@ -3,13 +3,13 @@
 """
 import asyncio
 import traceback
+from asyncio import get_running_loop
 from typing import Any, Awaitable, Callable, Optional, TextIO, cast
 
 import asyncssh
 
 from prompt_toolkit.application.current import AppSession, create_app_session
 from prompt_toolkit.data_structures import Size
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.input import PipeInput, create_pipe_input
 from prompt_toolkit.output.vt100 import Vt100_Output
 
@@ -75,7 +75,7 @@ def shell_requested(self) -> bool:
         return True
 
     def session_started(self) -> None:
-        self.interact_task = get_event_loop().create_task(self._interact())
+        self.interact_task = get_running_loop().create_task(self._interact())
 
     async def _interact(self) -> None:
         if self._chan is None:
@@ -141,7 +141,7 @@ async def interact(ssh_session: PromptToolkitSSHSession) -> None:
             print_formatted_text('You said: ', text)
 
         server = PromptToolkitSSHServer(interact=interact)
-        loop = get_event_loop()
+        loop = get_running_loop()
         loop.run_until_complete(
             asyncssh.create_server(
                 lambda: MySSHServer(interact),

src/prompt_toolkit/contrib/telnet/server.py

@@ -4,12 +4,12 @@
 import asyncio
 import socket
 import sys
+from asyncio import get_running_loop
 from typing import Any, Awaitable, Callable, List, Optional, Set, TextIO, Tuple, cast
 
 from prompt_toolkit.application.current import create_app_session, get_app
 from prompt_toolkit.application.run_in_terminal import run_in_terminal
 from prompt_toolkit.data_structures import Size
-from prompt_toolkit.eventloop import get_event_loop
 from prompt_toolkit.formatted_text import AnyFormattedText, to_formatted_text
 from prompt_toolkit.input import PipeInput, create_pipe_input
 from prompt_toolkit.output.vt100 import Vt100_Output
@@ -193,7 +193,7 @@ def handle_incoming_data() -> None:
                 self.close()
 
         # Add reader.
-        loop = get_event_loop()
+        loop = get_running_loop()
         loop.add_reader(self.conn, handle_incoming_data)
 
         try:
@@ -219,7 +219,7 @@ def close(self) -> None:
             self._closed = True
 
             self.vt100_input.close()
-            get_event_loop().remove_reader(self.conn)
+            get_running_loop().remove_reader(self.conn)
             self.conn.close()
             self.stdout.close()
 
@@ -310,11 +310,11 @@ def start(self) -> None:
             "Listening for telnet connections on %s port %r", self.host, self.port
         )
 
-        get_event_loop().add_reader(self._listen_socket, self._accept)
+        get_running_loop().add_reader(self._listen_socket, self._accept)
 
     async def stop(self) -> None:
         if self._listen_socket:
-            get_event_loop().remove_reader(self._listen_socket)
+            get_running_loop().remove_reader(self._listen_socket)
             self._listen_socket.close()
 
         # Wait for all applications to finish.
@@ -379,5 +379,5 @@ async def run() -> None:
             finally:
                 self._application_tasks.remove(task)
 
-        task = get_event_loop().create_task(run())
+        task = get_running_loop().create_task(run())
         self._application_tasks.append(task)