Create global instance of command-line options

This eases testing of option values inside the code.  This instance
is implemented as the read-only copy of the obtained 'options' object,
so callers won't be able to modify its contents.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

docs/doc-src/API.rst

@@ -60,3 +60,30 @@ An :class:`accounts.Account` connects two email repositories that are to be sync
    This execption inherits directly from :exc:`Exception` and is raised
    on errors during the offlineimap execution. It has an attribute
    `severity` that denotes the severity level of the error.
+
+
+:mod:`offlineimap.globals` -- module with global variables
+==========================================================
+
+.. module:: offlineimap.globals
+
+Module :mod:`offlineimap.globals` provides the read-only storage
+for the global variables.
+
+All exported module attributes can be set manually, but this practice
+is highly discouraged and shouldn't be used.
+However, attributes of all stored variables can only be read, write
+access to them is denied.
+
+Currently, we have only :attr:`options` attribute that holds
+command-line options as returned by OptionParser.
+The value of :attr:`options` must be set by :func:`set_options`
+prior to its first use.
+
+.. automodule:: offlineimap.globals
+   :members:
+
+   .. data:: options
+
+      You can access the values of stored options using the usual
+      syntax, offlineimap.globals.options.<option-name>

offlineimap/accounts.py

@@ -15,6 +15,7 @@
 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
 from offlineimap import mbnames, CustomConfig, OfflineImapError
+from offlineimap import globals
 from offlineimap.repository import Repository
 from offlineimap.ui import getglobalui
 from offlineimap.threadutil import InstanceLimitedThread
@@ -321,7 +322,7 @@ class SyncableAccount(Account):
                     self.ui.debug('', "Not syncing filtered folder '%s'"
                                  "[%s]" % (localfolder, localfolder.repository))
                     continue # Ignore filtered folder
-                if self.config.get('general', 'single-thread') == 'False':
+                if not globals.options.singlethreading:
                     thread = InstanceLimitedThread(\
                         instancename = 'FOLDER_' + self.remoterepos.getname(),
                         target = syncfolder,

offlineimap/folder/Base.py

@@ -16,6 +16,7 @@
 #    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
 from offlineimap import threadutil
+from offlineimap import globals
 from offlineimap.ui import getglobalui
 from offlineimap.error import OfflineImapError
 import offlineimap.accounts
@@ -403,7 +404,7 @@ class BaseFolder(object):
                 break
             self.ui.copyingmessage(uid, num+1, num_to_copy, self, dstfolder)
             # exceptions are caught in copymessageto()
-            if self.suggeststhreads() and self.config.get('general', 'single-thread') == 'False':
+            if self.suggeststhreads() and not globals.options.singlethreading:
                 self.waitforthread()
                 thread = threadutil.InstanceLimitedThread(\
                     self.getcopyinstancelimit(),

offlineimap/globals.py

@@ -0,0 +1,12 @@
+# Copyright 2013 Eygene A. Ryabinkin.
+#
+# Module that holds various global objects.
+
+from offlineimap.utils import const
+
+# Holds command-line options for OfflineIMAP.
+options = const.ConstProxy()
+
+def set_options (source):
+	""" Sets the source for options variable """
+	options.set_source (source)

offlineimap/init.py

@@ -25,6 +25,7 @@ import logging
 from optparse import OptionParser
 import offlineimap
 from offlineimap import accounts, threadutil, syncmaster
+from offlineimap import globals
 from offlineimap.error import OfflineImapError
 from offlineimap.ui import UI_LIST, setglobalui, getglobalui
 from offlineimap.CustomConfig import CustomConfigParser
@@ -161,6 +162,7 @@ class OfflineImap:
               ", ".join(UI_LIST.keys()))
 
         (options, args) = parser.parse_args()
+        globals.set_options (options)
 
         #read in configuration file
         configfilename = os.path.expanduser(options.configfile)
@@ -251,9 +253,6 @@ class OfflineImap:
                 if type.lower() == 'imap':
                     imaplib.Debug = 5
 
-        # XXX: can we avoid introducing fake configuration item?
-        config.set_if_not_exists('general', 'single-thread', 'True' if options.singlethreading else 'False')
-
         if options.runonce:
             # FIXME: maybe need a better
             for section in accounts.getaccountlist(config):

offlineimap/utils/const.py

@@ -0,0 +1,40 @@
+# Copyright 2013 Eygene A. Ryabinkin.
+#
+# Collection of classes that implement const-like behaviour
+# for various objects.
+
+import copy
+
+class ConstProxy (object):
+	"""
+	Implements read-only access to a given object
+	that can be attached to each instance only once.
+
+	"""
+
+	def __init__ (self):
+		self.__dict__['__source'] = None
+
+
+	def __getattr__ (self, name):
+		src = self.__dict__['__source']
+		if src == None:
+			raise ValueError ("using non-initialized ConstProxy() object")
+		return copy.deepcopy (getattr (src, name))
+
+
+	def __setattr__ (self, name, value):
+		raise AttributeError ("tried to set '%s' to '%s' for constant object" % \
+		  (name, value))
+
+
+	def __delattr__ (self, name):
+		raise RuntimeError ("tried to delete field '%s' from constant object" % \
+		  (name))
+
+
+	def set_source (self, source):
+		""" Sets source object for this instance. """
+		if (self.__dict__['__source'] != None):
+			raise ValueError ("source object is already set")
+		self.__dict__['__source'] = source

test/tests/test_00_globals.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+# Copyright 2013 Eygene A. Ryabinkin
+
+from offlineimap import globals
+import unittest
+
+class Opt:
+	def __init__(self):
+		self.one = "baz"
+		self.two = 42
+		self.three = True
+
+
+class TestOfflineimapGlobals(unittest.TestCase):
+
+	@classmethod
+	def setUpClass(klass):
+		klass.o = Opt()
+		globals.set_options (klass.o)
+
+	def test_initial_state(self):
+		for k in self.o.__dict__.keys():
+			self.assertTrue(getattr(self.o, k) ==
+			  getattr(globals.options, k))
+
+	def test_object_changes(self):
+		self.o.one = "one"
+		self.o.two = 119
+		self.o.three = False
+		return self.test_initial_state()
+
+	def test_modification(self):
+		with self.assertRaises(AttributeError):
+			globals.options.two = True
+
+	def test_deletion(self):
+		with self.assertRaises(RuntimeError):
+			del globals.options.three
+
+	def test_nonexistent_key(self):
+		with self.assertRaises(AttributeError):
+			a = globals.options.nosuchoption
+
+	def test_double_init(self):
+		with self.assertRaises(ValueError):
+			globals.set_options (True)
+
+
+if __name__ == "__main__":
+	suite = unittest.TestLoader().loadTestsFromTestCase(TestOfflineimapGlobals)
+	unittest.TextTestRunner(verbosity=2).run(suite)