Add callback registering.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/leap/common/events/__init__.py b/src/leap/common/events/__init__.py
new file mode 100644
index 0000000..27542a9
--- /dev/null
+++ b/src/leap/common/events/__init__.py
@@ -0,0 +1,51 @@
+# -*- coding: utf-8 -*-
+# __init__.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+from leap.common.events import (
+    signal_pb2,
+)
+
+
+# the `registered_callbacks` dictionary below should have the following
+# format:
+#
+#     { component: [ (uid, callback), ... ], ... }
+#
+registered_callbacks = {}
+
+
+def register(signal, callback, uid=None, replace=False):
+    """
+    Registers `callback` to be called when `signal` is signaled.
+    """
+    if not registered_callbacks.has_key(signal):
+        registered_callbacks[signal] = []
+    cbklist = registered_callbacks[signal]
+    if uid and filter(lambda (x,y): x == uid, cbklist):
+        # TODO: create appropriate exception
+        if not replace:
+            raise Exception("Callback already registered.")
+        else:
+            registered_callbacks[signal] = filter(lambda(x,y): x != uid,
+                                                  cbklist)
+    registered_callbacks[signal].append((uid, callback))
+    return uid
+
+#def get_registered_callbacks():
+#    return registered_callbacks
+
+#__all__ = ['signal_pb2', 'service', 'register', 'registered_callbacks']