1 files changed, 149 insertions, 0 deletions
diff --git a/configshell/prefs.py b/configshell/prefs.py
new file mode 100644
index 0000000..9ddb420
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+++ b/configshell/prefs.py
@@ -0,0 +1,149 @@
+'''
+This file is part of ConfigShell Community Edition.
+Copyright (c) 2011 by RisingTide Systems LLC
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, version 3 (AGPLv3).
+
+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 Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+'''
+
+import cPickle
+
+class Prefs(object):
+    '''
+    This is a preferences backend object used to:
+        - Hold the ConfigShell preferences
+        - Handle persistent storage and retrieval of these preferences
+        - Share the preferences between the ConfigShell and ConfigNode objects
+
+    As it is inherently destined to be shared between objects, this is a Borg.
+    '''
+    _prefs = {}
+    filename = None
+    autosave = False
+    __borg_state = {}
+
+    def __init__(self, filename=None):
+        '''
+        Instanciates the ConfigShell preferences object.
+        @param filename: File to store the preferencces to.
+        @type filename: str
+        '''
+        self.__dict__ = self.__borg_state
+        if filename is not None:
+            self.filename = filename
+
+    def __getitem__(self, key):
+        '''
+        Proxies dict-like references to prefs.
+        One specific behavior, though, is that if the key does not exists,
+        we will return None instead of raising an exception.
+        @param key: The preferences dictionnary key to get.
+        @type key: any valid dict key
+        @return: The key value
+        @rtype: n/a
+        '''
+        if key in self._prefs:
+            return self._prefs[key]
+        else:
+            return None
+
+    def __setitem__(self, key, value):
+        '''
+        Proxies dict-like references to prefs.
+        @param key: The preferences dictionnary key to set.
+        @type key: any valid dict key
+        '''
+        self._prefs[key] = value
+        if self.autosave:
+            self.save()
+
+    def __contains__(self, key):
+        '''
+        Do the preferences contain key ?
+        @param key: The preferences dictionnary key to check.
+        @type key: any valid dict key
+        '''
+        if key in self._prefs:
+            return True
+        else:
+            return False
+
+    def __delitem__(self, key):
+        '''
+        Deletes a preference key.
+        @param key: The preference to delete.
+        @type key: any valid dict key
+        '''
+        del self._prefs[key]
+        if self.autosave:
+            self.save()
+
+    def __iter__(self):
+        '''
+        Generic iterator for the preferences.
+        '''
+        return self._prefs.__iter__()
+
+    # Public methods
+
+    def keys(self):
+        '''
+        @return: Returns the list of keys in preferences.
+        @rtype: list
+        '''
+        return self._prefs.keys()
+
+    def items(self):
+        '''
+        @return: Returns the list of items in preferences.
+        @rtype: list of (key, value) tuples
+        '''
+        return self._prefs.items()
+
+    def iteritems(self):
+        '''
+        @return: Iterates on the items in preferences.
+        @rtype: yields items that are (key, value) pairs
+        '''
+        return self._prefs.iteritems()
+
+    def save(self, filename=None):
+        '''
+        Saves the preferences to disk. If filename is not specified,
+        use the default one if it is set, else do nothing.
+        @param filename: Optional alternate file to use.
+        @type filename: str
+        '''
+        if filename is None:
+            filename = self.filename
+
+        if filename is not None:
+            fsock = open(filename, 'wb')
+            try:
+                cPickle.dump(self._prefs, fsock, 2)
+            finally:
+                fsock.close()
+
+    def load(self, filename=None):
+        '''
+        Loads the preferences from file. Use either the supplied filename,
+        or the default one if set. Else, do nothing.
+        '''
+        if filename is None:
+            filename = self.filename
+
+        if filename is not None:
+            fsock = open(filename, 'rb')
+            try:
+                self._prefs = cPickle.load(fsock)
+            finally:
+                fsock.close()