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- """Generic interface to all dbm clones.
- Instead of
- import dbm
- d = dbm.open(file, 'w', 0666)
- use
- import anydbm
- d = anydbm.open(file, 'w')
- The returned object is a dbhash, gdbm, dbm or dumbdbm object,
- dependent on the type of database being opened (determined by whichdb
- module) in the case of an existing dbm. If the dbm does not exist and
- the create or new flag ('c' or 'n') was specified, the dbm type will
- be determined by the availability of the modules (tested in the above
- order).
- It has the following interface (key and data are strings):
- d[key] = data # store data at key (may override data at
- # existing key)
- data = d[key] # retrieve data at key (raise KeyError if no
- # such key)
- del d[key] # delete data stored at key (raises KeyError
- # if no such key)
- flag = key in d # true if the key exists
- list = d.keys() # return a list of all existing keys (slow!)
- Future versions may change the order in which implementations are
- tested for existence, and add interfaces to other dbm-like
- implementations.
- """
- class error(Exception):
- pass
- _names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm']
- _errors = [error]
- _defaultmod = None
- for _name in _names:
- try:
- _mod = __import__(_name)
- except ImportError:
- continue
- if not _defaultmod:
- _defaultmod = _mod
- _errors.append(_mod.error)
- if not _defaultmod:
- raise ImportError, "no dbm clone found; tried %s" % _names
- error = tuple(_errors)
- def open(file, flag='r', mode=0666):
- """Open or create database at path given by *file*.
- Optional argument *flag* can be 'r' (default) for read-only access, 'w'
- for read-write access of an existing database, 'c' for read-write access
- to a new or existing database, and 'n' for read-write access to a new
- database.
- Note: 'r' and 'w' fail if the database doesn't exist; 'c' creates it
- only if it doesn't exist; and 'n' always creates a new database.
- """
- # guess the type of an existing database
- from whichdb import whichdb
- result=whichdb(file)
- if result is None:
- # db doesn't exist
- if 'c' in flag or 'n' in flag:
- # file doesn't exist and the new
- # flag was used so use default type
- mod = _defaultmod
- else:
- raise error, "need 'c' or 'n' flag to open new db"
- elif result == "":
- # db type cannot be determined
- raise error, "db type could not be determined"
- else:
- mod = __import__(result)
- return mod.open(file, flag, mode)
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