linux - Unable to initialize a window and wait for a process to end in Python 3 + GTK+ 3 -

i'm new object-oriented programming, python , gtk+3, though have decent knowledge of procedural programming (mainly c).

i'm trying build simple python + gtk+ 3 script run pkexec apt-get update under linux.

i have mainwindow class (based on gtk.window class) contains button object named button (based on gtk.button class) triggers new_update_window() method defined in mainwindow upon clicked event;

the new_update_window() method initializes updatewindow object updatewindow class (based on gtk.window class) contains label object named label (based on gtk.label class) , calls methods show_all() , update() defined in updatewindow;

the update() method supposed change label, run pkexec apt-get update , change label again.

the problem no matter 1 of following occurs:

• if run subprocess.popen(["/usr/bin/pkexec", "/usr/bin/apt-get", "update"]) directly, update.window shown label set value should set after pkexec apt-get update has finished executing;
• if run subprocess.call(["/usr/bin/pkexec", "/usr/bin/apt-get", "update"]) directly, update.window not shown until pkexec apt-get update has finished executing;
• i tried importing threading, defining separate run_update() method in updatewindow , start function in separate thread using thread = threading.thread(target=self.run_update), thread.start(), thread.join(), still depending on method call in run_update() (subprocess.call() or subprocess.popen) relative behavior described above exhibits.

tl;dr

i'm @ loss understand how accomplish i'm after, is:

1. showing updatewindow (gtk.window)
2. updating label (gtk.label) in updatewindow
3. running pkexec apt-get update
4. updating label in updatewindow

• subprocess.popen(): update.window shown label set value should set after pkexec apt-get update has finished executing;
• subprocess.call(): update.window not shown until pkexec apt-get update has finished executing;
• wrapping either of 2 in function , run function in separate thread doesn't change anything.

here's code;

not using thread (case 1, in case using subprocess.popen()):

#!/usr/bin/python3 gi.repository import gtk import subprocess  class mainwindow(gtk.window):      def __init__(self):         gtk.window.__init__(self, title = "updater")          button = gtk.button()         button.set_label("update")         button.connect("clicked", self.new_update_window)         self.add(button)      def new_update_window(self, button):         update = updatewindow()         update.show_all()         update.update()  class updatewindow(gtk.window):      def __init__(self):         gtk.window.__init__(self, title = "updating...")          self.label = gtk.label()         self.label.set_text("idling...")         self.add(self.label)      def update(self):         self.label.set_text("updating... please wait.")         subprocess.call(["/usr/bin/pkexec", "/usr/bin/apt-get", "update"])         self.label.set_text("updated.")      def run_update(self):  main = mainwindow() main.connect("delete-event", gtk.main_quit) main.show_all() gtk.main() 

using thread (case 3, in case using subprocess.popen()):

#!/usr/bin/python3 gi.repository import gtk import threading import subprocess  class mainwindow(gtk.window):      def __init__(self):         gtk.window.__init__(self, title = "updater")          button = gtk.button()         button.set_label("update")         button.connect("clicked", self.new_update_window)         self.add(button)      def new_update_window(self, button):         update = updatewindow()         update.show_all()         update.update()  class updatewindow(gtk.window):      def __init__(self):         gtk.window.__init__(self, title = "updating...")          self.label = gtk.label()         self.label.set_text("idling...")         self.add(self.label)      def update(self):         self.label.set_text("updating... please wait.")         thread = threading.thread(target=self.run_update)         thread.start()         thread.join()         self.label.set_text("updated.")      def run_update(self):         subprocess.popen(["/usr/bin/pkexec", "/usr/bin/apt-get", "update"])  main = mainwindow() main.connect("delete-event", gtk.main_quit) main.show_all() gtk.main() 

instead of using python's subprocess module, use gio.subprocess integrates gtk's main loop:

#!/usr/bin/python3 gi.repository import gtk, gio  # ...  class updatewindow(gtk.window):      def __init__(self):         gtk.window.__init__(self, title="updating...")          self.label = gtk.label()         self.label.set_text("idling...")         self.add(self.label)      def update(self):         self.label.set_text("updating... please wait.")         subprocess = gio.subprocess.new(["/usr/bin/pkexec", "/usr/bin/apt-get", "update"], 0)         subprocess.wait_check_async(none, self._on_update_finished)      def _on_update_finished(self, subprocess, result):         subprocess.wait_check_finish(result)         self.label.set_text("updated.")