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, and add interfaces to other dbm-like |
---|
33 | implementations. |
---|
34 | """ |
---|
35 | |
---|
36 | class error(Exception): |
---|
37 | pass |
---|
38 | |
---|
39 | _names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm'] |
---|
40 | _errors = [error] |
---|
41 | _defaultmod = None |
---|
42 | |
---|
43 | for _name in _names: |
---|
44 | try: |
---|
45 | _mod = __import__(_name) |
---|
46 | except ImportError: |
---|
47 | continue |
---|
48 | if not _defaultmod: |
---|
49 | _defaultmod = _mod |
---|
50 | _errors.append(_mod.error) |
---|
51 | |
---|
52 | if not _defaultmod: |
---|
53 | raise ImportError, "no dbm clone found; tried %s" % _names |
---|
54 | |
---|
55 | error = tuple(_errors) |
---|
56 | |
---|
57 | def open(file, flag='r', mode=0666): |
---|
58 | """Open or create database at path given by *file*. |
---|
59 | |
---|
60 | Optional argument *flag* can be 'r' (default) for read-only access, 'w' |
---|
61 | for read-write access of an existing database, 'c' for read-write access |
---|
62 | to a new or existing database, and 'n' for read-write access to a new |
---|
63 | database. |
---|
64 | |
---|
65 | Note: 'r' and 'w' fail if the database doesn't exist; 'c' creates it |
---|
66 | only if it doesn't exist; and 'n' always creates a new database. |
---|
67 | """ |
---|
68 | |
---|
69 | # guess the type of an existing database |
---|
70 | from whichdb import whichdb |
---|
71 | result=whichdb(file) |
---|
72 | if result is None: |
---|
73 | # db doesn't exist |
---|
74 | if 'c' in flag or 'n' in flag: |
---|
75 | # file doesn't exist and the new |
---|
76 | # flag was used so use default type |
---|
77 | mod = _defaultmod |
---|
78 | else: |
---|
79 | raise error, "need 'c' or 'n' flag to open new db" |
---|
80 | elif result == "": |
---|
81 | # db type cannot be determined |
---|
82 | raise error, "db type could not be determined" |
---|
83 | else: |
---|
84 | mod = __import__(result) |
---|
85 | return mod.open(file, flag, mode) |
---|