I wonder why pyqtSignal() is used. (pyqt, QThread, signal, slot) - pyqt

Question

This is the test code about QThread and Signal.
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
import time
import sys
class Thread1(QThread):
set_signal = pyqtSignal(int) # (1) ##
def __init__(self, parent):
super().__init__(parent)
def run(self):
for i in range(10):
time.sleep(1)
self.set_signal.emit(i) # (3) ##
class MainWidget(QWidget):
def __init__(self):
super().__init__()
thread_start = QPushButton("시 작!")
thread_start.clicked.connect(self.increaseNumber)
vbox = QVBoxLayout()
vbox.addWidget(thread_start)
self.resize(200,200)
self.setLayout(vbox)
def increaseNumber(self):
x = Thread1(self)
x.set_signal.connect(self.print) # (2) ##
x.start()
def print(self, number):
print(number)
if __name__ == '__main__':
app = QApplication(sys.argv)
widget = MainWidget()
widget.show()
sys.exit(app.exec_())
In the example of QThread I searched for, a pyqtSignal()(step 1) object was created, the desired slot function was connected(step 2) by connect, and then called by emit()(step 3).
I don't know the difference from calling the desired method immediately without connecting the connect().

Answer 1

So, the goal of codes is triggering a desired function every second. You are right about it.
But if you create multiple objects, you can connect it to different desired functions. Or connect multiple function to one signal.
x = Thread1(self)
x.set_signal.connect(self.print) # (2) ##
x.start()
y = Thread1(self)
y.set_signal.connect(self.print2)
time.sleep(0.5)
y.start()