def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def handleevent(self):
        """
        Event-handler for the 'widgets' demo
        """
        while True:
            event = self.dialog.waitForEvent()
            if event.eventType() == yui.YEvent.CancelEvent:
                self.dialog.destroy()
                break
            if event.widget() == self.closebutton:
                info = Info("Quit confirmation", 1, "Are you sure you want to quit?")
                if self.ask_YesOrNo(info):
                    self.dialog.destroy()
                    break
            if event.widget() == self.aboutbutton:
                self.aboutDialog()