I want to run an external script (demo_print.py) and print the output in real-time in a text widget.

I got error:

What's my mistake and how to reach my goal ? You can suggest more simple solution if you have.

Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/bin/python3/3.7.4/lib/python3.7/threading.py", line 926, in _bootstrap_inner
self.run()
File "/usr/bin/python3/3.7.4/lib/python3.7/threading.py", line 870, in run
self._target(*self._args, **self._kwargs)
File "example_gui.py", line 37, in test
textbox.insert(tk.END, msg   "\n")
File "example_gui.py", line 20, in write
self.widget.insert('end', textbox)
File "/usr/bin/python3/3.7.4/lib/python3.7/tkinter/__init__.py", line 3272, in insert
self.tk.call((self._w, 'insert', index, chars)   args)
_tkinter.TclError: out of stack space (infinite loop?)

I want to run an external script (demo_print.py) and print the output in real-time in a text widget.

example_gui.py

import tkinter as tk
import subprocess
import threading
import sys
from functools import partial


# ### classes ####

class Redirect:

    def __init__(self, widget, autoscroll=True):
        self.widget = widget
        self.autoscroll = autoscroll

    def write(self, textbox):
        self.widget.insert('end', textbox)
        if self.autoscroll:
            self.widget.see('end')  # autoscroll

    def flush(self):
        pass


def run(textbox=None):
    threading.Thread(target=test, args=[textbox]).start()


def test(textbox=None):
    p = subprocess.Popen("demo_print.py", stdout=subprocess.PIPE, bufsize=1, text=True)
    while p.poll() is None:
        msg = p.stdout.readline().strip()  # read a line from the process output
        if msg:
            textbox.insert(tk.END, msg   "\n")


if __name__ == "__main__":
    fenster = tk.Tk()
    fenster.title("My Program")
    textbox = tk.Text(fenster)
    textbox.grid()
    scrollbar = tk.Scrollbar(fenster, orient=tk.VERTICAL)
    scrollbar.grid()

    textbox.config(yscrollcommand=scrollbar.set)
    scrollbar.config(command=textbox.yview)

    start_button = tk.Button(fenster, text="Start", command=partial(run, textbox))
    start_button.grid()

    old_stdout = sys.stdout
    sys.stdout = Redirect(textbox)

    fenster.mainloop()
    sys.stdout = old_stdout

demo_print.py

import time
for i in range(10):
    print(f"print {i}")
    time.sleep(1)

CodePudding user response：

Okay so first of all make sure demo_print.py is in the same space as your main.py not in a folder or anything then you can just do this:

from demo_print import *
print(whatever u named your output variable in demo_print)

From the looks of it you know how to do the rest.

CodePudding user response：

Since you execute "demo_print.py" directly, so it must be executable and has correct shebang (for example, #!/usr/bin/python -u) in the file.

However, I would suggest to execute the file using Python executable instead. Also the Redirect class is not necessary for your case.

Below is the modified code:

import tkinter as tk
import subprocess
import threading
import sys
from functools import partial


def run(textbox=None):
    threading.Thread(target=test, args=[textbox]).start()


def test(textbox=None):
    # using the Python executable to run demo_print.py
    p = subprocess.Popen([sys.executable, "-u", "demo_print.py"], stdout=subprocess.PIPE, bufsize=1, text=True)
    while p.poll() is None:
        msg = p.stdout.readline().strip()  # read a line from the process output
        if msg:
            textbox.insert(tk.END, msg   "\n")
            textbox.see(tk.END)


if __name__ == "__main__":
    fenster = tk.Tk()
    fenster.title("My Program")
    textbox = tk.Text(fenster)
    textbox.grid(row=0, column=0)
    scrollbar = tk.Scrollbar(fenster, orient=tk.VERTICAL)
    scrollbar.grid(row=0, column=1, sticky="ns")

    textbox.config(yscrollcommand=scrollbar.set)
    scrollbar.config(command=textbox.yview)

    start_button = tk.Button(fenster, text="Start", command=partial(run, textbox))
    start_button.grid()

    fenster.mainloop()