Exposing serial data functionally through a plugin

platypush/backend/serial/__init__.py

@@ -1,40 +1,50 @@
 import logging
 import serial
+import tempfile
 import time
 
 from platypush.backend import Backend
 from platypush.message.event.serial import SerialDataEvent
 
-
 class SerialBackend(Backend):
-    state = None
-
     def __init__(self, device, baud_rate=9600, **kwargs):
         super().__init__(**kwargs)
 
         self.device = device
         self.baud_rate = baud_rate
         self.serial = None
+        self.data = None
+        self.tmp_file = tempfile.TemporaryFile()
 
     def send_message(self, msg):
         pass
 
-    def get_state(self):
-        return self.state
+    def get_data(self):
+        self.tmp_file.seek(0)
+        data = self.tmp_file.read()
+        self.tmp_file.seek(0)
+
+        return data.decode('utf-8')
 
     def run(self):
         super().run()
 
         self.serial = serial.Serial(self.device, self.baud_rate)
-        prev_value = None
         logging.info('Initialized serial backend on device {}'.format(self.device))
 
+        try:
             while not self.should_stop():
-            value = self.serial.readline().decode('utf-8').strip()
-            if prev_value is None or value != prev_value:
-                self.bus.post(SerialDataEvent(data=value, device=self.device))
+                new_data = self.serial.readline().decode('utf-8').strip()
+                if self.data is None or self.data != new_data:
+                    self.bus.post(SerialDataEvent(data=new_data, device=self.device))
 
-            prev_value = value
+                self.data = new_data
+
+                self.tmp_file.seek(0)
+                self.tmp_file.write(self.data.encode('utf-8'))
+                self.tmp_file.seek(0)
+        finally:
+            self.tmp_file.close()
 
 
 # vim:sw=4:ts=4:et:

platypush/plugins/serial/__init__.py

@@ -0,0 +1,16 @@
+from platypush.context import get_backend
+from platypush.message.response import Response
+
+from .. import Plugin
+
+class SerialPlugin(Plugin):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    def get_data(self):
+        backend = get_backend('serial')
+        return Response(output=backend.get_data())
+
+
+# vim:sw=4:ts=4:et:
+