[ASync] Help Wanted - Proper Python Design Pattern

[MikeTheWatchGuy]

I don't really "get" the Python asynch capability well enough to understand how to incorporate it into PySimpleGUI.

My current asynch capability is achieved by performing a "Read with Timeout". This is, in essence, a poll. It's an efficient poll, but it's still a form of polling.

Can someone make some suggestions of how the async/await constructs could be used to benefit the user of PySimpleGUI?

I'm looking for SIMPLE ideas and simple implementations that can be shared in the demo section or perhaps a change made to the core code itself to help support.

If you have some suggestions o r solution, by all means speak up!

[iforvard]

What would not hang the window when downloading this demo?
https://github.com/PySimpleGUI/PySimpleGUI/blob/master/DemoPrograms/Demo_Youtube-dl_Frontend.py

[MikeTheWatchGuy]

What needs to happen in any PySimpleGUI program is that a Read or Refresh is called on a periodic basis. It can even be "infrequent", but needs to be called or else windows eventually reports the window as being unresponsive even though your code is running just fine.

One way to get periodic calls to Window.Refresh() is to tie it to the output of the program that's being spun out as a subprocess.

For programs like these, where you're spinning out a subprocess, try this function to execute the subprocess. I used it for the EXEMaker for example. You'll want an OutputElement somewhere in your layout to give the text some place to go.

def runCommand(cmd, timeout=None, window=None):
    """ run shell command

	@param cmd: command to execute
	@param timeout: timeout for command execution

	@return: (return code from command, command output)
	"""

    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    output = ''
    for line in p.stdout:
        line = line.decode(errors='replace' if (sys.version_info) < (3, 5)
                           else 'backslashreplace').rstrip()
        output += line
        print(line)
        if window:
            window.Refresh()

    retval = p.wait(timeout)

    return (retval, output)

[mozesa]

Dear MikeTheWatchGuy,

I would like to ask for your kind help.

Is it possible to use asyncio with PySimpleGUI.
I have a project in which there are a lot of I/O operation.
I would like to use Trio with PySimpleGui.

Thanks for your help.

[PySimpleGUI]

I'm not sure it would buy anything.

PySimpleGUI is quite low-level in terms of the I/O. You have basically a single read command to get your events,. And you call Update methods to change Element settings. That's really all there is to it. You can set a timeout for the read. It's much like Python's Queue object.

Let me know what you come up with.

[PySimpleGUI]

If you have a project with a lot of I/O, there are many ways to do this in PySimpleGUI. One is to run your event loop in a way that doesn't block and perhaps does "refreshes" throughout your I/O.

If the amount of time it takes to get through your I/O is too long for 1 event loop to handle, there are ways to do this using threads. You'll find a few demo programs that show you how you can coordinate communication between threads and PySimpleGUI by using a Queue.

Take a look at this PySimpleGUI program running on Trinket. The demo uses the same thread code for each thread. You can use any number of your own threads. They don't all have to do the same thing. And because they're threads, they can block for as long as you want them to.

https://pysimplegui.trinket.io/demo-programs#/demo-programs/multi-threaded-work

[mozesa]

The best word is PySimpleGui is awesome.

The below snippet use trio, asyncio with PySimpleGui and it works like a charm.

import trio
from datetime import datetime

import PySimpleGUI as sg


async def main() -> None:
    window = sg.Window(
        "Test",
        layout=[[sg.Button("Test", key="_TEST_")]],
        default_element_size=(100, 100),
        grab_anywhere=True,
        finalize=True,
    )
    while True:
        event, values = window.read(timeout=20)

        if event is None:
            break

        elif event == "_TEST_":
            print("Test")

        await trio.sleep(0.0)
    window.Close()


async def func() -> None:
    print(f"Enter {func=} function at {datetime.now()}.")
    await trio.sleep(10)
    print(f"Exit at {datetime.now()}")


async def parent() -> None:
    async with trio.open_nursery() as nursery:
        nursery.start_soon(main)
        nursery.start_soon(func)
        print(f"{parent=} here.")
    print(f"{parent=} exit.")

trio.run(parent)

[EvokerKing]

The best word is PySimpleGui is awesome.

The below snippet use trio, asyncio with PySimpleGui and it works like a charm.

import trio
from datetime import datetime

import PySimpleGUI as sg


async def main() -> None:
    window = sg.Window(
        "Test",
        layout=[[sg.Button("Test", key="_TEST_")]],
        default_element_size=(100, 100),
        grab_anywhere=True,
        finalize=True,
    )
    while True:
        event, values = window.read(timeout=20)

        if event is None:
            break

        elif event == "_TEST_":
            print("Test")

        await trio.sleep(0.0)
    window.Close()


async def func() -> None:
    print(f"Enter {func=} function at {datetime.now()}.")
    await trio.sleep(10)
    print(f"Exit at {datetime.now()}")


async def parent() -> None:
    async with trio.open_nursery() as nursery:
        nursery.start_soon(main)
        nursery.start_soon(func)
        print(f"{parent=} here.")
    print(f"{parent=} exit.")

trio.run(parent)

So is window.read(timeout=20) 20 seconds, 20 milliseconds or something else.

[jason990420]

You can find it in Call Reference - Window

:param timeout: Milliseconds to wait until the Read will return IF no other GUI events happen first
:type timeout: (int)