cpython-withatomic / Doc / libanydbm.tex

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\section{Standard Modules \sectcode{anydbm} and  \sectcode{dumbdbm}}

\code{anydbm} is a generic interface to variants of the DBM
database--DBM, GDBM, or dbhash.  If none of these modules is
installed, the slow-but-simple implementation in module \code{dumbdbm}
will be used.   Both modules provide the same interface:

% not the best solution, but it's what you get for documenting both
% at the same time.
\renewcommand{\indexsubitem}{(in modules anydbm, dumbdbm)}

\begin{funcdesc}{open}{filename\optional{\, flag\, mode}}
Open the database file \var{filename} and return a corresponding object.  
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).

The object returned by \code{open()} supports most of the same
functionality as dictionaries; keys and their corresponding values can
be stored, retrieved, and deleted, and the \code{has_key()} and
\code{keys()} methods are available.  Keys and values must always be

Both modules also export the exception \code{error}, which is raised
for various problems.  The \code{anydbm.error} exception is simply a
different name for the \code{error} exception of the underlying
implementation module used.