output_redirect - GitPress.io

Example Python program output_redirect.py This program creates a PyQt GUI Python version 3.x or newer. To check the Python version use:

python --version

Modules

import sys
import time
from multiprocessing import Pipe, Process
from PyQt5.QtCore import QThread, QMetaObject, Q_ARG
from PyQt5.QtWidgets import *

Classes

class PipeOutput(object):
class TextEditDispatcher(QThread):

Methods

def init(self, pipe):
def write(self, s):
def flush(self):
def print_name(pipe, name):
def init(self):
def add_connection(self, widget, pipe):
def run(self):

Code

Example Python PyQt program :

#!/usr/bin/env python3
import sys
import time
from multiprocessing import Pipe, Process
from PyQt5.QtCore import QThread, QMetaObject, Q_ARG
from PyQt5.QtWidgets import *

# Example is a quite ugly, but works

class PipeOutput(object):
    def __init__(self, pipe):
        self.pipe = pipe
    def write(self, s):
        self.pipe.send(s)
    def flush(self):
        pass

def print_name(pipe, name):
    sys.stdout = PipeOutput(pipe)
    while True:
        print('Process name: ' + name)
        time.sleep(0.5)


class TextEditDispatcher(QThread):
    def __init__(self):
        QThread.__init__(self)
        self.connections = []

    def add_connection(self, widget, pipe):
        self.connections.append((widget, pipe))

    def run(self):
        while (True):
            for widget, pipe in self.connections:
                if pipe.poll():
                    text = pipe.recv().strip()
                    QMetaObject.invokeMethod(widget, 'append', Q_ARG(str, text))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = QSplitter()
    out_a = QTextEdit()
    out_b = QTextEdit()
    window.addWidget(out_a)
    window.addWidget(out_b)
    window.show()

    cna_recv, cna_send = Pipe(False)
    cnb_recv, cnb_send = Pipe(False)

    proc_a = Process(target=print_name, args=(cna_send, 'Alice'))
    proc_b = Process(target=print_name, args=(cnb_send, 'Bob'))

    proc_a.start()
    proc_b.start()

    dsp = TextEditDispatcher()
    dsp.add_connection(out_a, cna_recv)
    dsp.add_connection(out_b, cnb_recv)
    dsp.start()

    ret = app.exec_()
    proc_a.terminate()
    proc_b.terminate()
    sys.exit(ret)

Useful Links

Articles: https://python-commandments.org/
PyQt: https://pythonpyqt.com/
Tutorial: https://pythonprogramminglanguage.com/