[modules] Initial module loading framework

Add a very simplistic framework for loading modules that query system
data. The user can provide a list of modules via an argument switch, and
the name of the module is used to look up a Python module that has to
have a class called "Module".

The outer framework (the outputs, in particular) then uses various query
methods of that class to construct a meaningful output.

i3bumblebee

@@ -1,18 +1,46 @@
 #!/usr/bin/env python
 
+import sys
+import time
+import argparse
+import importlib
 import bumblebee.outputs.i3
 
+def print_module_list():
+    # TODO
+    pass
+
 def main():
+    parser = argparse.ArgumentParser(description="display system data in the i3bar")
+    parser.add_argument("-m", "--modules", nargs="+", help="List of modules to load. The order of the list determines their order in the i3bar (from left to right)")
+    parser.add_argument("-l", "--list", action="store_true", help="List all available modules")
+
+    args = parser.parse_args()
+
+    if args.list:
+        print_module_list()
+        sys.exit(0)
+
+    modules = []
+    for m in args.modules:
+        # TODO: how to cleanly handle errors here?
+        # (useful error messages)
+        module = importlib.import_module("bumblebee.modules.%s" % m)
+        modules.append(getattr(module, "Module")())
+
     output = bumblebee.outputs.i3.i3bar()
 
-    print output.preamble()
+    print output.start()
+    sys.stdout.flush()
 
     while True:
-        # TODO: retrieve data from modules
-        data = []
-        print output.data(data)
+        for m in modules:
+            output.add(m)
+        print output.get()
+        sys.stdout.flush()
+        time.sleep(1)
 
-    print output.finalize()
+    print output.stop()
 
 if __name__ == "__main__":
     main()