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index ee73759d26ceb41a003f90111d56fa3b65c2c4c9..1fc794888400e87c30a1df4ad50dd61ac872ef0e 100644 (file)
# FOR A PARTICULAR PURPOSE. THE CODE PROVIDED HEREUNDER IS ON AN "AS IS"
# BASIS, AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
# SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
-#
-# $Id: __init__.py,v 1.12 2002-05-22 00:32:33 richard Exp $
+#
+# $Id: __init__.py,v 1.40 2007-11-07 20:47:12 richard Exp $
-__all__ = []
+'''Container for the hyperdb storage backend implementations.
+'''
+__docformat__ = 'restructuredtext'
-try:
- import sys, anydbm
- if not hasattr(sys, 'version_info') or sys.version_info < (2,1,2):
- import dumbdbm
- # dumbdbm only works in python 2.1.2+
- assert anydbm._defaultmod != dumbdbm
- del anydbm
- del dumbdbm
-except AssertionError:
- print "WARNING: you should upgrade to python 2.1.3"
-except ImportError, message:
- if str(message) != 'No module named anydbm': raise
-else:
- import back_anydbm
- anydbm = back_anydbm
- __all__.append('anydbm')
+import sys
-try:
- import bsddb
-except ImportError, message:
- if str(message) != 'No module named bsddb': raise
-else:
- import back_bsddb
- bsddb = back_bsddb
- __all__.append('bsddb')
+# These names are used to suppress import errors.
+# If get_backend raises an ImportError with appropriate
+# module name, have_backend quietly returns False.
+# Otherwise the error is reraised.
+_modules = {
+ 'mysql': ('MySQLdb',),
+ 'postgresql': ('psycopg',),
+ 'tsearch2': ('psycopg',),
+ 'sqlite': ('pysqlite', 'pysqlite2', 'sqlite3', '_sqlite3', 'sqlite'),
+}
-try:
- import bsddb3
-except ImportError, message:
- if str(message) != 'No module named bsddb3': raise
-else:
- import back_bsddb3
- bsddb3 = back_bsddb3
- __all__.append('bsddb3')
+def get_backend(name):
+ '''Get a specific backend by name.'''
+ vars = globals()
+ # if requested backend has been imported yet, return current instance
+ if name in vars:
+ return vars[name]
+ # import the backend module
+ module_name = 'back_%s' % name
+ try:
+ module = __import__(module_name, vars)
+ except:
+ # import failed, but in versions prior to 2.4, a (broken)
+ # module is left in sys.modules and package globals;
+ # subsequent imports would succeed and get the broken module.
+ # This no longer happens in Python 2.4 and later.
+ if sys.version_info < (2, 4):
+ del sys.modules['.'.join((__name__, module_name))]
+ del vars[module_name]
+ raise
+ else:
+ vars[name] = module
+ return module
-#
-# $Log: not supported by cvs2svn $
-# Revision 1.11 2002/02/16 08:39:42 richard
-# . #516854 ] "My Issues" and redisplay
-#
-# Revision 1.10 2002/01/22 07:08:50 richard
-# I was certain I'd already done this (there's even a change note in
-# CHANGES)...
-#
-# Revision 1.9 2001/12/12 02:30:51 richard
-# I fixed the problems with people whose anydbm was using the dbm module at the
-# backend. It turns out the dbm module modifies the file name to append ".db"
-# and my check to determine if we're opening an existing or new db just
-# tested os.path.exists() on the filename. Well, no longer! We now perform a
-# much better check _and_ cope with the anydbm implementation module changing
-# too!
-# I also fixed the backends __init__ so only ImportError is squashed.
-#
-# Revision 1.8 2001/12/10 22:20:01 richard
-# Enabled transaction support in the bsddb backend. It uses the anydbm code
-# where possible, only replacing methods where the db is opened (it uses the
-# btree opener specifically.)
-# Also cleaned up some change note generation.
-# Made the backends package work with pydoc too.
-#
-# Revision 1.7 2001/12/10 00:57:38 richard
-# From CHANGES:
-# . Added the "display" command to the admin tool - displays a node's values
-# . #489760 ] [issue] only subject
-# . fixed the doc/index.html to include the quoting in the mail alias.
-#
-# Also:
-# . fixed roundup-admin so it works with transactions
-# . disabled the back_anydbm module if anydbm tries to use dumbdbm
-#
-# Revision 1.6 2001/08/07 00:24:42 richard
-# stupid typo
-#
-# Revision 1.5 2001/08/07 00:15:51 richard
-# Added the copyright/license notice to (nearly) all files at request of
-# Bizar Software.
-#
-#
-#
-# vim: set filetype=python ts=4 sw=4 et si
+def have_backend(name):
+ '''Is backend "name" available?'''
+ if name == 'tsearch2':
+ # currently not working
+ return 0
+ try:
+ get_backend(name)
+ return 1
+ except ImportError, e:
+ for name in _modules.get(name, (name,)):
+ if str(e).startswith('No module named %s'%name):
+ return 0
+ raise
+ return 0
+
+def list_backends():
+ '''List all available backend names.
+
+ This function has side-effect of registering backward-compatible
+ globals for all available backends.
+
+ '''
+ l = []
+ for name in 'anydbm', 'mysql', 'sqlite', 'postgresql':
+ if have_backend(name):
+ l.append(name)
+ return l
+
+# vim: set filetype=python sts=4 sw=4 et si :