ref: 88ccea37f65b87312292b2b1a107c39927c6a2c3
dir: /sys/src/cmd/python/Doc/lib/libanydbm.tex/
\section{\module{anydbm} --- Generic access to DBM-style databases} \declaremodule{standard}{anydbm} \modulesynopsis{Generic interface to DBM-style database modules.} \module{anydbm} is a generic interface to variants of the DBM database --- \refmodule{dbhash}\refstmodindex{dbhash} (requires \refmodule{bsddb}\refbimodindex{bsddb}), \refmodule{gdbm}\refbimodindex{gdbm}, or \refmodule{dbm}\refbimodindex{dbm}. If none of these modules is installed, the slow-but-simple implementation in module \refmodule{dumbdbm}\refstmodindex{dumbdbm} will be used. \begin{funcdesc}{open}{filename\optional{, flag\optional{, mode}}} Open the database file \var{filename} and return a corresponding object. If the database file already exists, the \refmodule{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 \var{flag} argument can be \code{'r'} to open an existing database for reading only, \code{'w'} to open an existing database for reading and writing, \code{'c'} to create the database if it doesn't exist, or \code{'n'}, which will always create a new empty database. If not specified, the default value is \code{'r'}. The optional \var{mode} argument is the \UNIX{} mode of the file, used only when the database has to be created. It defaults to octal \code{0666} (and will be modified by the prevailing umask). \end{funcdesc} \begin{excdesc}{error} A tuple containing the exceptions that can be raised by each of the supported modules, with a unique exception \exception{anydbm.error} as the first item --- the latter is used when \exception{anydbm.error} is raised. \end{excdesc} The object returned by \function{open()} supports most of the same functionality as dictionaries; keys and their corresponding values can be stored, retrieved, and deleted, and the \method{has_key()} and \method{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: \begin{verbatim} 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() \end{verbatim} \begin{seealso} \seemodule{dbhash}{BSD \code{db} database interface.} \seemodule{dbm}{Standard \UNIX{} database interface.} \seemodule{dumbdbm}{Portable implementation of the \code{dbm} interface.} \seemodule{gdbm}{GNU database interface, based on the \code{dbm} interface.} \seemodule{shelve}{General object persistence built on top of the Python \code{dbm} interface.} \seemodule{whichdb}{Utility module used to determine the type of an existing database.} \end{seealso}