[core] Widget creation/update overhaul

Until now, widgets were re-created during each iteration. For multiple,
reasons, using static widget objects is much easier, so instead of
creating new widgets continuously, modules now create the widgets during
instantiation and get the list of widgets passed as parameter whenever
an update occurs. During the update, they can still manipulate the
widget list by removing and adding elements as needed.

Advantages:
* Less memory fragmentation (fewer (de)allocations)
* Easier event management (widgets now have static IDs)
* Easier module code (widget contents can simply be the result of a
  callback)

see #23

bumblebee/engine.py

@@ -12,8 +12,14 @@ class Module(object):
     (e.g. CPU utilization, disk usage, etc.) derive from
     this base class.
     """
-    def __init__(self, engine):
-        pass
+    def __init__(self, engine, widgets):
+        self._widgets = []
+        if widgets:
+            self._widgets = widgets if isinstance(widgets, list) else [widgets]
+
+    def widgets(self):
+        """Return the widgets to draw for this module"""
+        return self._widgets
 
 class Engine(object):
     """Engine for driving the application
@@ -53,11 +59,9 @@ class Engine(object):
         """Start the event loop"""
         self._output.start()
         while self.running():
-            widgets = []
             for module in self._modules:
-                module_widgets = module.widgets()
-                widgets += module_widgets if isinstance(module_widgets, list) else [module_widgets]
-            self._output.draw(widgets=widgets, engine=self)
+                module.update(module.widgets())
+                self._output.draw(widgets=module.widgets(), engine=self)
             self._output.flush()
             if self.running():
                 time.sleep(1)

bumblebee/modules/cpu.py

@@ -7,12 +7,15 @@ import bumblebee.engine
 
 class Module(bumblebee.engine.Module):
     def __init__(self, engine):
-        super(Module, self).__init__(engine)
+        super(Module, self).__init__(engine,
+            bumblebee.output.Widget(full_text=self.utilization)
+        )
         self._utilization = psutil.cpu_percent(percpu=False)
 
-    def widgets(self):
-        self._utilization = psutil.cpu_percent(percpu=False)
+    def utilization(self):
+        return "{:05.02f}%".format(self._utilization)
 
-        return bumblebee.output.Widget(full_text="{:05.02f}%".format(self._utilization))
+    def update(self, widgets):
+        self._utilization = psutil.cpu_percent(percpu=False)
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/modules/test.py

@@ -6,9 +6,11 @@ import bumblebee.engine
 
 class Module(bumblebee.engine.Module):
     def __init__(self, engine):
-        super(Module, self).__init__(engine)
+        super(Module, self).__init__(engine,
+            bumblebee.output.Widget(full_text="test")
+        )
 
-    def widgets(self):
-        return bumblebee.output.Widget(full_text="test")
+    def update(self, widgets):
+        pass
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/output.py

@@ -12,7 +12,10 @@ class Widget(object):
 
     def full_text(self):
         """Retrieve the full text to display in the widget"""
-        return self._full_text
+        if callable(self._full_text):
+            return self._full_text()
+        else:
+            return self._full_text
 
 class I3BarOutput(object):
     """Manage output according to the i3bar protocol"""

bumblebee/theme.py

@@ -1,6 +1,7 @@
 """Theme support"""
 
 class Theme(object):
+    """Represents a collection of icons and colors"""
     pass
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

runlint.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-find . -name "*.py"|xargs pylint --disable=R0903,R0201
+find . -name "*.py"|xargs pylint --disable=R0903,R0201,C0330

tests/modules/test_cpu.py

@@ -10,7 +10,14 @@ class TestCPUModule(unittest.TestCase):
         self.module = Module(None)
 
     def test_widgets(self):
-        widget = self.module.widgets()
-        assertWidgetAttributes(self, widget)
+        widgets = self.module.widgets()
+        for widget in widgets:
+            assertWidgetAttributes(self, widget)
+
+    def test_update(self):
+        widgets = self.module.widgets()
+        self.module.update(widgets)
+        self.test_widgets()
+        self.assertEquals(widgets, self.module.widgets())
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

tests/test_module.py

@@ -0,0 +1,25 @@
+# pylint: disable=C0103,C0111,W0703
+
+import unittest
+
+from bumblebee.engine import Module
+from tests.util import MockWidget
+
+class TestModule(unittest.TestCase):
+    def setUp(self):
+        self.widget = MockWidget("foo")
+        self.moduleWithoutWidgets = Module(engine=None, widgets=None)
+        self.moduleWithOneWidget = Module(engine=None, widgets=self.widget)
+        self.moduleWithMultipleWidgets = Module(engine=None,
+            widgets=[self.widget, self.widget, self.widget]
+        )
+
+    def test_empty_widgets(self):
+        self.assertEquals(self.moduleWithoutWidgets.widgets(), [])
+
+    def test_single_widget(self):
+        self.assertEquals(self.moduleWithOneWidget.widgets(), [self.widget])
+
+    def test_multiple_widgets(self):
+        for widget in self.moduleWithMultipleWidgets.widgets():
+            self.assertEquals(widget, self.widget)

tests/util.py

@@ -23,6 +23,9 @@ class MockWidget(object):
     def __init__(self, text):
         self._text = text
 
+    def update(self, widgets):
+        pass
+
     def full_text(self):
         return self._text