Simple example of the correct way to use (Py)Qt(5) and QThread

threads1.py

# Copyright (c) 2016 Rob Kent (jazzycamel)
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
# and associated documentation files (the "Software"), to deal in the Software without restriction, 
# including without limitation the rights to use, copy, modify, merge, publish, distribute, 
# sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is 
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all copies or 
# substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT 
# NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
# DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from itertools import count, islice

class Threaded(QObject):
    result=pyqtSignal(int)

    def __init__(self, parent=None, **kwargs):
        super().__init__(parent, **kwargs)

    @pyqtSlot()
    def start(self): print("Thread started")

    @pyqtSlot(int)
    def calculatePrime(self, n):
        primes=(n for n in count(2) if all(n % d for d in range(2, n)))
        self.result.emit(list(islice(primes, 0, n))[-1])

class GUI(QWidget):
    requestPrime=pyqtSignal(int)

    def __init__(self, parent=None, **kwargs):
        super().__init__(parent, **kwargs)

        self._thread=QThread()
        self._threaded=Threaded(result=self.displayPrime)
        self.requestPrime.connect(self._threaded.calculatePrime)
        self._thread.started.connect(self._threaded.start)
        self._threaded.moveToThread(self._thread)
        qApp.aboutToQuit.connect(self._thread.quit)
        self._thread.start()

        l=QVBoxLayout(self)
        self._iterationLE=QLineEdit(self, placeholderText="Iteration (n)")
        l.addWidget(self._iterationLE)
        self._requestBtn=QPushButton(
            "Calculate Prime", self, clicked=self.primeRequested)
        l.addWidget(self._requestBtn)
        self._busy=QProgressBar(self)
        l.addWidget(self._busy)
        self._resultLbl=QLabel("Result:", self)
        l.addWidget(self._resultLbl)

    @pyqtSlot()
    def primeRequested(self):
        try: n=int(self._iterationLE.text())
        except: return
        self.requestPrime.emit(n)
        self._busy.setRange(0,0)
        self._iterationLE.setEnabled(False)
        self._requestBtn.setEnabled(False)

    @pyqtSlot(int)
    def displayPrime(self, prime):
        self._resultLbl.setText("Result: {}".format(prime))
        self._busy.setRange(0,100)
        self._iterationLE.setEnabled(True)
        self._requestBtn.setEnabled(True)

if __name__=="__main__":
    from sys import exit, argv

    a=QApplication(argv)
    g=GUI()
    g.show()
    exit(a.exec_())

Hi @jazzycamel

I would like to use the contents of this git in pyqtgraph's documentation with citation. Would you be so kind to put a license to your example(s) so I can properly cite?

Thank you so much for posting these.

@j9ac9k I've added the MIT license as a header to the original gist code. Hope this is what you need, glad this has been useful and thanks very much for the citation, much appreciated.

@j9ac9k I've added the MIT license as a header to the original gist code. Hope this is what you need, glad this has been useful and thanks very much for the citation, much appreciated.

That's perfect, thank you so much!

And it's in our docs: https://pyqtgraph.readthedocs.io/en/latest/getting_started/qtcrashcourse.html#id8

Thanks!