[PATCH 7/8] Improve repository/Maildir.getfolder() to use cached objects

[Sebastian Spaeth]

Previously, getfolder() would always construct new MaildirFolder()
objects, independent of whether the folder exists or not. Improve the
function to:

1) Scan and cache the folders if not already done
2) Return the same cached object if we ask for the same foldername twice
3) Reduce a tiny bit of code duplication

This is important because we handle stuff like folderfilter in the
scandir function and if we discard the scanned dir and create a new
object on folderget(), we will lose the folderfilter information.

Signed-off-by: Sebastian Spaeth <Sebastian at SSpaeth.de>
---
 offlineimap/repository/Maildir.py |   21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/offlineimap/repository/Maildir.py b/offlineimap/repository/Maildir.py
index ef3a723..6b0736b 100644
--- a/offlineimap/repository/Maildir.py
+++ b/offlineimap/repository/Maildir.py
@@ -19,6 +19,7 @@
 from Base import BaseRepository
 from offlineimap import folder
 from offlineimap.ui import getglobalui
+from offlineimap.error import OfflineImapError
 import os
 from stat import *
 
@@ -110,12 +111,20 @@ class MaildirRepository(BaseRepository):
         self.ui.warn("NOT YET IMPLEMENTED: DELETE FOLDER %s" % foldername)
 
     def getfolder(self, foldername):
-        if self.config.has_option('Repository ' + self.name, 'restoreatime') and self.config.getboolean('Repository ' + self.name, 'restoreatime'):
-            self._append_folder_atimes(foldername)
-        return folder.Maildir.MaildirFolder(self.root, foldername,
-                                            self.getsep(), self, 
-                                            self.accountname, self.config)
-    
+        """Return a Folder instance of this Maildir
+
+        If necessary, scan and cache all foldernames to make sure that
+        we only return existing folders and that 2 calls with the same
+        name will return the same object."""
+        # getfolders() will scan and cache the values *if* necessary
+        folders = self.getfolders()
+        for folder in folders:
+            if foldername == folder.name:
+                return folder
+        raise OfflineImapError("getfolder() asked for a nonexisting "
+                               "folder '%s'." % foldername,
+                               OfflineImapError.ERROR.FOLDER)
+
     def _getfolders_scandir(self, root, extension = None):
         """Recursively scan folder 'root'; return a list of MailDirFolder
 
-- 
1.7.4.1