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anydbm is a generic interface to variants of the DBM
database -- dbhash (requires
bsddb),
gdbm, or
dbm. If none of these modules is
installed, the slow-but-simple implementation in module
dumbdbm will be used.
| open( |
filename[, flag[, mode]]) |
-
Open the database file filename and return a corresponding object.
If the database file already exists, the whichdb module is
used to determine its type and the appropriate module is used; if it
does not exist, the first module listed above that can be imported is
used.
The optional flag argument can be
'r' to open an existing database for reading only,
'w' to open an existing database for reading and writing,
'c' to create the database if it doesn't exist, or
'n', which will always create a new empty database. If not
specified, the default value is 'r'.
The optional mode argument is the Unix mode of the file, used
only when the database has to be created. It defaults to octal
0666 (and will be modified by the prevailing umask).
- exception error
-
A tuple containing the exceptions that can be raised by each of the
supported modules, with a unique exception anydbm.error as
the first item -- the latter is used when anydbm.error is
raised.
The object returned by open() supports most of the same
functionality as dictionaries; keys and their corresponding values can
be stored, retrieved, and deleted, and the has_key() and
keys() methods are available. Keys and values must always be
strings.
The following example records some hostnames and a corresponding title,
and then prints out the contents of the database:
import anydbm
# Open database, creating it if necessary.
db = anydbm.open('cache', 'c')
# Record some values
db['www.python.org'] = 'Python Website'
db['www.cnn.com'] = 'Cable News Network'
# Loop through contents. Other dictionary methods
# such as .keys(), .values() also work.
for k, v in db.iteritems():
print k, '\t', v
# Storing a non-string key or value will raise an exception (most
# likely a TypeError).
db['www.yahoo.com'] = 4
# Close when done.
db.close()
See Also:
- Module dbhash:
- BSD
db database interface.
- Module dbm:
- Standard Unix database interface.
- Module dumbdbm:
- Portable implementation of the
dbm interface.
- Module gdbm:
- GNU database interface, based on the
dbm interface.
- Module shelve:
- General object persistence built on top of
the Python
dbm interface.
- Module whichdb:
- Utility module used to determine the type of an
existing database.
Release 2.5.2, documentation updated on 21th February, 2008.
See About this document... for information on suggesting changes.
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