| 1 | """Generic interface to all dbm clones. |
| 2 | |
| 3 | Instead of |
| 4 | |
| 5 | import dbm |
| 6 | d = dbm.open(file, 'w', 0666) |
| 7 | |
| 8 | use |
| 9 | |
| 10 | import anydbm |
| 11 | d = anydbm.open(file, 'w') |
| 12 | |
| 13 | The returned object is a dbhash, gdbm, dbm or dumbdbm object, |
| 14 | dependent on the type of database being opened (determined by whichdb |
| 15 | module) in the case of an existing dbm. If the dbm does not exist and |
| 16 | the create or new flag ('c' or 'n') was specified, the dbm type will |
| 17 | be determined by the availability of the modules (tested in the above |
| 18 | order). |
| 19 | |
| 20 | It has the following interface (key and data are strings): |
| 21 | |
| 22 | d[key] = data # store data at key (may override data at |
| 23 | # existing key) |
| 24 | data = d[key] # retrieve data at key (raise KeyError if no |
| 25 | # such key) |
| 26 | del d[key] # delete data stored at key (raises KeyError |
| 27 | # if no such key) |
| 28 | flag = key in d # true if the key exists |
| 29 | list = d.keys() # return a list of all existing keys (slow!) |
| 30 | |
| 31 | Future versions may change the order in which implementations are |
| 32 | tested for existence, add interfaces to other dbm-like |
| 33 | implementations. |
| 34 | |
| 35 | The open function has an optional second argument. This can be 'r', |
| 36 | for read-only access, 'w', for read-write access of an existing |
| 37 | database, 'c' for read-write access to a new or existing database, and |
| 38 | 'n' for read-write access to a new database. The default is 'r'. |
| 39 | |
| 40 | Note: 'r' and 'w' fail if the database doesn't exist; 'c' creates it |
| 41 | only if it doesn't exist; and 'n' always creates a new database. |
| 42 | |
| 43 | """ |
| 44 | |
| 45 | class error(Exception): |
| 46 | pass |
| 47 | |
| 48 | _names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm'] |
| 49 | _errors = [error] |
| 50 | _defaultmod = None |
| 51 | |
| 52 | for _name in _names: |
| 53 | try: |
| 54 | _mod = __import__(_name) |
| 55 | except ImportError: |
| 56 | continue |
| 57 | if not _defaultmod: |
| 58 | _defaultmod = _mod |
| 59 | _errors.append(_mod.error) |
| 60 | |
| 61 | if not _defaultmod: |
| 62 | raise ImportError, "no dbm clone found; tried %s" % _names |
| 63 | |
| 64 | error = tuple(_errors) |
| 65 | |
| 66 | def open(file, flag = 'r', mode = 0666): |
| 67 | # guess the type of an existing database |
| 68 | from whichdb import whichdb |
| 69 | result=whichdb(file) |
| 70 | if result is None: |
| 71 | # db doesn't exist |
| 72 | if 'c' in flag or 'n' in flag: |
| 73 | # file doesn't exist and the new |
| 74 | # flag was used so use default type |
| 75 | mod = _defaultmod |
| 76 | else: |
| 77 | raise error, "need 'c' or 'n' flag to open new db" |
| 78 | elif result == "": |
| 79 | # db type cannot be determined |
| 80 | raise error, "db type could not be determined" |
| 81 | else: |
| 82 | mod = __import__(result) |
| 83 | return mod.open(file, flag, mode) |