Example using greenlets to provide a blocking interface to asynchronously accept values from a GUI.

gtk_input_greenlet.py

'''
Example using greenlets to provide a blocking interface to asynchronously
accept values from a GUI.
'''
import gtk
from pygtkhelpers.delegates import WindowView
from greenlet import greenlet


class View(WindowView):
    def __init__(self):
        self.entry_callback_greenlet = None
        super(View, self).__init__()

    def create_ui(self):
        self.widget = gtk.Window()
        box = gtk.VBox()
        self.button = gtk.Button()
        self.button.set_label('Push me')
        self.text_input = gtk.Entry()
        box.pack_start(self.text_input)
        box.pack_start(self.button)
        self.widget.add(box)
        self.entry_callback_greenlet = greenlet(self.process_commands)
        self.entry_callback_greenlet.switch()

    def on_widget__delete_event(self, window, event):
        self.hide_and_quit()

    def on_button__clicked(self, *args):
        if self.entry_callback_greenlet is not None:
            # Return current text input contents to `read_next_char` parent.
            self.entry_callback_greenlet.switch(self.text_input.get_text())

    def read_next_char(self):
        g_self = greenlet.getcurrent()
        self.text_input.set_text('')
        # Jump to the parent (GTK thread), waiting for the next input value.
        # __NB__ This is a blocking call.
        next_char = g_self.parent.switch()
        return next_char

    def process_commands(self):
        while True:
            print 'GOT: ', self.read_next_char()


if __name__ == '__main__':
    view = View()
    view.show_and_run()