klippy: Convert printer_state("disconnect") to an event handler

Convert all users of the printer_state("disconnect") handler to
register a "klippy:disconnect" event handler instead.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/gcode.py

@@ -17,6 +17,8 @@ class GCodeParser:
         self.printer = printer
         self.fd = fd
         printer.register_event_handler("klippy:shutdown", self.handle_shutdown)
+        printer.register_event_handler("klippy:disconnect",
+                                       self.handle_disconnect)
         # Input handling
         self.reactor = printer.get_reactor()
         self.is_processing_data = False
@@ -122,10 +124,10 @@ class GCodeParser:
         if self.is_fileinput:
             self.printer.request_exit('error_exit')
         self._respond_state("Shutdown")
+    def handle_disconnect(self):
+        self._respond_state("Disconnect")
     def printer_state(self, state):
         if state != 'ready':
-            if state == 'disconnect':
-                self._respond_state("Disconnect")
             return
         self.is_printer_ready = True
         self.gcode_handlers = self.ready_gcode_handlers

klippy/mcu.py

@@ -423,6 +423,8 @@ class MCU:
         if self._name.startswith('mcu '):
             self._name = self._name[4:]
         self._printer.register_event_handler("klippy:shutdown", self._shutdown)
+        self._printer.register_event_handler("klippy:disconnect",
+                                             self._disconnect)
         # Serial port
         self._serialport = config.get('serial', '/dev/ttyS0')
         baud = 0
@@ -768,8 +770,6 @@ class MCU:
     def printer_state(self, state):
         if state == 'connect':
             self._connect()
-        elif state == 'disconnect':
-            self._disconnect()
     def __del__(self):
         self._disconnect()