[core/output] Start implementation of a partial update

Add a "patch()" method that eventually will only update affected
modules.

bumblebee-status

@@ -11,13 +11,14 @@ import core.output
 import core.module
 import core.input
 
-def handle_input():
+def handle_input(output):
     poll = select.poll()
     poll.register(sys.stdin.fileno(), select.POLLIN)
 
     while True:
         events = poll.poll()
 
+        modules = {}
         for fileno, event in events:
             line = '['
             while line.startswith('['):
@@ -26,8 +27,11 @@ def handle_input():
             try:
                 event = json.loads(line)
                 core.input.trigger(event)
+                if 'name' in event:
+                    modules[event['name']] = True
             except ValueError:
                 pass
+        output.draw('patch', modules.keys())
 
     poll.unregister(sys.stdin.fileno())
 
@@ -42,7 +46,7 @@ def main():
     output = core.output.i3()
     modules = []
 
-    input_thread = threading.Thread(target=handle_input)
+    input_thread = threading.Thread(target=handle_input, args=(output,))
     input_thread.daemon = True
     input_thread.start()
 
@@ -51,7 +55,6 @@ def main():
     output.modules(modules)
     output.draw('start')
     while True:
-        output.clear()
         for module in modules:
             module.update()
         output.draw('statusline')

core/output.py

@@ -5,15 +5,16 @@ import time
 class i3(object):
     def __init__(self):
         self._modules = []
-        self.clear()
+        self._status = []
 
     def modules(self, modules=None):
         if not modules:
             return self._modules
         self._modules = modules if isinstance(modules, list) else [ modules ]
 
-    def draw(self, what):
-        data = getattr(self, what)()
+    def draw(self, what, args=None):
+        cb = getattr(self, what)
+        data = cb(args) if args else cb()
         if 'data' in data:
             sys.stdout.write(json.dumps(data['data']))
         if 'suffix' in data:
@@ -30,20 +31,20 @@ class i3(object):
     def stop(self):
         return { 'suffix': '\n]' }
 
-    def clear(self):
-        self._statusline = []
+    def patch(self, affected_modules):
+        pass # TODO
 
     def statusline(self):
-        status = []
+        self._status = []
         for module in self._modules:
             for widget in module.widgets():
-                status.append({
+                self._status.append({
                     'full_text': widget.full_text(),
                     'instance': widget.id(),
                     'name': module.id(),
                 })
         return {
-            'data': status,
+            'data': self._status,
             'suffix': ','
         }