myList.py

import sys

from PyQt5.QtWidgets import QApplication, QListWidget, QMainWindow


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("My App")

        self.widget = QListWidget()
        self.widget.addItems(["One", "Two", "Three"])
        for i in range(1,50):
            self.widget.addItem("New Item " + str(i))

        # In QListWidget there are two separate signals for the item, and the str
        self.widget.currentItemChanged.connect(self.index_changed)
        # self.widget.currentTextChanged.connect(self.text_changed)

        self.setCentralWidget(self.widget)

    def index_changed(self, i):  # Not an index, i is a QListItem
        print(self.widget.currentRow())

    def text_changed(self, s):  # s is a str
        print(s)

app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec_()