#
# Copyright (c) 2001 Bizar Software Pty Ltd (http://www.bizarsoftware.com.au/)
# This module is free software, and you may redistribute it and/or modify
# under the same terms as Python, so long as this copyright message and
# disclaimer are retained in their original form.
#
# IN NO EVENT SHALL BIZAR SOFTWARE PTY LTD BE LIABLE TO ANY PARTY FOR
# DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING
# OUT OF THE USE OF THIS CODE, EVEN IF THE AUTHOR HAS BEEN ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# BIZAR SOFTWARE PTY LTD SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
# BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# 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 1.40 2007-11-07 20:47:12 richard Exp $
'''Container for the hyperdb storage backend implementations.
'''
__docformat__ = 'restructuredtext'
import sys
# 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'),
}
def get_backend(name):
'''Get a specific backend by name.'''
vars = globals()
# if requested backend has been imported yet, return current instance
if vars.has_key(name):
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
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 :
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