Question: gradual transition from standard command line application with prints() to textual app

[menteora]

Hi, I've been using this library recently, and it seems fantastic.

I would like to gradually manage the transition from a command-line app to a textual app. Therefore, I would like to convert all the initial print() statements in the old app into prints within a textual window with a header and footer. Is it possible?

from textual.app import App, ComposeResult
from textual.widgets import RichLog
from textual.widgets import Header, Footer
from textual.containers import VerticalScroll

class RichLogApp(App):
    def compose(self) -> ComposeResult:
        yield Header(self.title)
        yield Footer()
        yield VerticalScroll(
            RichLog(highlight=True, markup=True)
        )

    def print(self, message):
        text_log = self.query_one(RichLog)
        text_log.write(message)

if __name__ == "__main__":
    app = RichLogApp()
    app.run()
    app.print('your message here')
    app.print('your message here 2')

Of course, the code I've written doesn't work because the run() function is blocking the execution of the code.

Is there a way to achieve the result I'm looking for?

Thank you

[davep]

You can use print capturing and direct the output to your app, a screen or a specific widget. For example:

from textual.app import App, ComposeResult
from textual.events import Print
from textual.widgets import Log

class PrintingApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Log()

    def on_print(self, event: Print) -> None:
        self.query_one(Log).write(event.text)

    def on_mount(self) -> None:
        self.begin_capture_print(self)
        print("Your message here")
        print("Your message here 2")

if __name__ == "__main__":
    PrintingApp().run()

[menteora]

Works! Thank you

[davep]

Glad to hear it worked, most welcome. :-)

[menteora]

Just to share, here's my implementation so I can use a standard dialog.

from textual.app import App, ComposeResult
from textual.widgets import Button, Log, Header, Footer
from textual.containers import VerticalScroll
from textual.events import Print
import importlib

class PrintLogDialog(App):

    CSS = """
        Button {
            width: 100%;
            height: auto;
            dock: bottom;
        }

        .header {
            margin: 2 2 2 2;
            text-style: bold;
        }
    """  

    def __init__(self, run_class, title='', run_method='run', data={}, ok_button_text='OK') -> None:
        super().__init__()
        self.run_class = run_class
        self.run_method = run_method
        self.data = data
        self.ok_button_text = ok_button_text
        self.title = title
        self.ret_code = None

    def compose(self) -> ComposeResult:
        yield Header(self.title)
        yield Footer()
        yield Log()
        yield Button(self.ok_button_text,variant="primary", id='confirm')

    def on_print(self, event: Print) -> None:
        self.query_one(Log).write(event.text)        

    def on_mount(self) -> None:
        module = importlib.import_module(self.run_class)
        self.begin_capture_print(self)
        func = getattr(module, self.run_method)
        if self.data == {}:
            self.ret_code = func()
        else:
            self.ret_code = func(self.data)

    def on_button_pressed(self, event: Button.Pressed) -> None:
        self.exit(self.ret_code)

if __name__ == "__main__":
    PrintLogDialog(run_class=folder.module', run_method='method').run()

[menteora]

Hello @davep , I have an issue with the sample code. The display of prints happens at the end of the code, not while the code is being executed. Is there a way to overcome this issue?

Example:

from textual.app import App, ComposeResult
from textual.events import Print
from textual.widgets import Log

class PrintingApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Log()

    def on_print(self, event: Print) -> None:
        self.query_one(Log).write(event.text)

    def on_mount(self) -> None:
        self.begin_capture_print(self)
        print("Your message here 1")
        time.sleep(10)
        print("Your message here 2")
        time.sleep(10)
        print("Your message here 3")

if __name__ == "__main__":
    PrintingApp().run()

[davep]

You're using time.sleep, which will block your application from processing messages, which means the print messages win't make it to the Log until on_mount has finished.

[menteora]

Thank you for your response @davep.

Yes, I have simplified the code, and sleep() simply simulates a process that takes time to reach the end of the mount(). In this case, until the process is finished, the user doesn't see anything, whereas in a standard application, they see the print() statements as the code is executed. Do you think there is a way to achieve the same thing?

[davep]

This is where you'll have to transition to a more Textual-like approach to your application; at the very least look at using the worker API to do the busy work. For example:

from time import sleep

from textual import work
from textual.app import App, ComposeResult
from textual.events import Print
from textual.widgets import Log

class PrintingApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Log()

    def on_print(self, event: Print) -> None:
        self.query_one(Log).write(event.text)

    def on_mount(self) -> None:
        self.begin_capture_print(self)
        self.do_busy_work()

    @work(thread=True)
    def do_busy_work(self):
        print("Your message here 1")
        sleep(10)
        print("Your message here 2")
        sleep(10)
        print("Your message here 3")

if __name__ == "__main__":
    PrintingApp().run()

[menteora]

@davep I think I've found solution.

from textual.app import App, ComposeResult
from textual.events import Print
from textual.widgets import Log
from textual import work
from time import sleep

class PrintingApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Log()

    def on_print(self, event: Print) -> None:
        self.query_one(Log).write(event.text)

    @work(thread=True)
    def run_my_worker(self):
        self.begin_capture_print(self)
        print("Your message here 1")
        time.sleep(5)
        print("Your message here 2")
        time.sleep(5)
        print("Your message here 3")

    def on_mount(self) -> None:
        self.run_my_worker()

if __name__ == "__main__":
    PrintingApp().run()

[menteora]

Wow! Same response, I've see now!
Thank you very mutch @davep !