Simple text editor with PyQt

edytor.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'E:\Development\Python\PyQt tests\text editor\edytor.ui'
#
# Created: Mon Apr 29 16:12:17 2013
#      by: PyQt4 UI code generator 4.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_edytor(object):
    def setupUi(self, edytor):
        edytor.setObjectName(_fromUtf8("edytor"))
        edytor.resize(451, 461)
        self.centralwidget = QtGui.QWidget(edytor)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.button_open = QtGui.QPushButton(self.centralwidget)
        self.button_open.setGeometry(QtCore.QRect(20, 10, 131, 31))
        self.button_open.setObjectName(_fromUtf8("button_open"))
        self.button_close = QtGui.QPushButton(self.centralwidget)
        self.button_close.setGeometry(QtCore.QRect(300, 10, 131, 31))
        self.button_close.setObjectName(_fromUtf8("button_close"))
        self.editor_window = QtGui.QTextEdit(self.centralwidget)
        self.editor_window.setGeometry(QtCore.QRect(20, 50, 411, 391))
        self.editor_window.setObjectName(_fromUtf8("editor_window"))
        self.button_save = QtGui.QPushButton(self.centralwidget)
        self.button_save.setEnabled(False)
        self.button_save.setGeometry(QtCore.QRect(160, 10, 131, 31))
        self.button_save.setObjectName(_fromUtf8("button_save"))
        edytor.setCentralWidget(self.centralwidget)

        self.retranslateUi(edytor)
        QtCore.QMetaObject.connectSlotsByName(edytor)

    def retranslateUi(self, edytor):
        edytor.setWindowTitle(_translate("edytor", "Edytor", None))
        self.button_open.setText(_translate("edytor", "Open File", None))
        self.button_close.setText(_translate("edytor", "Close", None))
        self.button_save.setText(_translate("edytor", "Save", None))

edytor_run.pyw

"""A simple text editor from a tutorial.

Originally obtained from http://www.rkblog.rk.edu.pl/w/p/simple-text-editor-pyqt4/
but modified for newer PyQt4 and Python 3.
"""
import sys
from os.path import isfile

from PyQt4.QtGui import QMessageBox, QApplication, QMainWindow, QFileDialog
from PyQt4.QtCore import pyqtSlot, QFileSystemWatcher

from edytor import Ui_edytor


class PyQtRunner(QApplication):
    apps = []

    def __init__(self, args=None, apps=None, exec_=False):
        if args is None:
            args = sys.argv
        super().__init__(args)

        if apps is not None:
            self.apps.extend(App() for App in apps)
        if exec_:
            self.exec_()

    def add(self, App):
        self.apps.append(App())
        return self

    def exec_(self):
        for a in self.apps:
            a.show()

        sys.exit(super().exec_())


class Edytor(QMainWindow, Ui_edytor):
    fpath = ""

    def __init__(self):
        super().__init__()
        self.setupUi(self)
        # Create watcher
        self.watcher = QFileSystemWatcher(self)

        # Register slots
        self.button_close.clicked.connect(self.close)
        self.button_open.clicked.connect(self.file_open)
        self.button_save.clicked.connect(self.file_save)
        self.editor_window.textChanged.connect(self.text_changed)
        self.watcher.fileChanged.connect(self.file_changed)

    @pyqtSlot()
    def file_open(self, fpath=""):
        if self.ask_discard():
            return

        fpath = fpath or QFileDialog.getOpenFileName(self, "Open file...")
        if isfile(fpath):
            # Switch watcher files
            if self.fpath:
                self.watcher.removePath(self.fpath)
            self.watcher.addPath(fpath)

            with open(fpath) as f:
                text = f.read()
            self.editor_window.setText(text)
            # Disable afterwards since `setText` triggers "textChanged" signal
            self.button_save.setEnabled(False)

            # Finally save the path
            self.fpath = fpath

    @pyqtSlot()
    def file_save(self):
        if isfile(self.fpath):
            # Do not trigger fileChanged when saving ourselves
            self.watcher.removePath(self.fpath)

            text = self.editor_window.toPlainText()
            with open(self.fpath, 'w') as f:
                f.write(text)

            self.button_save.setEnabled(False)
            self.watcher.addPath(self.fpath)

    @pyqtSlot()
    def text_changed(self):
        if self.fpath:
            self.button_save.setEnabled(True)

    @pyqtSlot(str)
    def file_changed(self, path):
        res = QMessageBox.question(
            self, "%s - File has been changed" % self.objectName(),
            "The opened document has been modified by another program.\n"
            + "Do you want to reload the file?",
            QMessageBox.Yes | QMessageBox.No
            | (QMessageBox.Save if self.button_save.isEnabled() else 0),
            QMessageBox.Yes
        )
        if res == QMessageBox.Yes:
            self.file_open(self.fpath)
        elif res == QMessageBox.Save:
            self.file_save()

    def ask_discard(self):
        if not self.button_save.isEnabled():
            return

        res = QMessageBox.question(
            self, "%s - Unsaved changes" % self.objectName(),
            "The document has been modified\n"
            + "Do you want to save your changes?",
            QMessageBox.Save | QMessageBox.Discard | QMessageBox.Cancel,
            QMessageBox.Save
        )
        print(res)
        if res == QMessageBox.Save:
            self.file_save()

        return res == QMessageBox.Cancel

    def closeEvent(self, event):
        # For some reason this is called twice when clicking the "Close" button SOMETIMES
        if self.ask_discard():
            event.ignore()
        else:
            event.accept()

if __name__ == "__main__":
    # PyQtRunner(None, (Edytor,), True)
    PyQtRunner().add(Edytor).exec_()