ref: 5b7d8e1f6fb4167e354545fef7e6dd6676986441
dir: /sys/src/cmd/python/Doc/lib/libdumbdbm.tex/
\section{\module{dumbdbm} ---
Portable DBM implementation}
\declaremodule{standard}{dumbdbm}
\modulesynopsis{Portable implementation of the simple DBM interface.}
\index{databases}
\begin{notice}
The \module{dumbdbm} module is intended as a last resort fallback for
the \refmodule{anydbm} module when no more robust module is available.
The \module{dumbdbm} module is not written for speed and is not nearly as
heavily used as the other database modules.
\end{notice}
The \module{dumbdbm} module provides a persistent dictionary-like interface
which is written entirely in Python. Unlike other modules such as
\refmodule{gdbm} and \refmodule{bsddb}, no external library is required. As
with other persistent mappings, the keys and values must always be strings.
The module defines the following:
\begin{excdesc}{error}
Raised on dumbdbm-specific errors, such as I/O errors. \exception{KeyError}
is raised for general mapping errors like specifying an incorrect key.
\end{excdesc}
\begin{funcdesc}{open}{filename\optional{, flag\optional{, mode}}}
Open a dumbdbm database and return a dumbdbm object. The \var{filename}
argument is the basename of the database file (without any specific
extensions). When a dumbdbm database is created, files with \file{.dat} and
\file{.dir} extensions are created.
The optional \var{flag} argument is currently ignored; the database is
always opened for update, and will be created if it does not exist.
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).
\versionchanged[The \var{mode} argument was ignored in earlier
versions]{2.2}
\end{funcdesc}
\begin{seealso}
\seemodule{anydbm}{Generic interface to \code{dbm}-style databases.}
\seemodule{dbm}{Similar interface to the DBM/NDBM library.}
\seemodule{gdbm}{Similar interface to the GNU GDBM library.}
\seemodule{shelve}{Persistence module which stores non-string data.}
\seemodule{whichdb}{Utility module used to determine the type of an
existing database.}
\end{seealso}
\subsection{Dumbdbm Objects \label{dumbdbm-objects}}
In addition to the methods provided by the \class{UserDict.DictMixin} class,
\class{dumbdbm} objects provide the following methods.
\begin{methoddesc}{sync}{}
Synchronize the on-disk directory and data files. This method is called by
the \method{sync} method of \class{Shelve} objects.
\end{methoddesc}