Doc/lib/libdbm.tex

   1 \section{\module{dbm} ---
   2          Simple ``database'' interface}
   3
   4 \declaremodule{builtin}{dbm}
   5   \platform{Unix}
   6 \modulesynopsis{The standard ``database'' interface, based on ndbm.}
   7
   8
   9 The \module{dbm} module provides an interface to the \UNIX{}
  10 \code{(n)dbm} library.  Dbm objects behave like mappings
  11 (dictionaries), except that keys and values are always strings.
  12 Printing a dbm object doesn't print the keys and values, and the
  13 \method{items()} and \method{values()} methods are not supported.
  14
  15 See also the \refmodule{gdbm}\refbimodindex{gdbm} module, which
  16 provides a similar interface using the GNU GDBM library.
  17
  18 The module defines the following constant and functions:
  19
  20 \begin{excdesc}{error}
  21 Raised on dbm-specific errors, such as I/O errors.
  22 \exception{KeyError} is raised for general mapping errors like
  23 specifying an incorrect key.
  24 \end{excdesc}
  25
  26 \begin{funcdesc}{open}{filename, \optional{flag, \optional{mode}}}
  27 Open a dbm database and return a dbm object.  The \var{filename}
  28 argument is the name of the database file (without the \file{.dir} or
  29 \file{.pag} extensions).
  30
  31 The optional \var{flag} argument can be
  32 \code{'r'} (to open an existing database for reading only --- default),
  33 \code{'w'} (to open an existing database for reading and writing),
  34 \code{'c'} (which creates the database if it doesn't exist), or
  35 \code{'n'} (which always creates a new empty database).
  36
  37 The optional \var{mode} argument is the \UNIX{} mode of the file, used
  38 only when the database has to be created.  It defaults to octal
  39 \code{0666}.
  40 \end{funcdesc}
  41
  42
  43 \begin{seealso}
  44   \seemodule{anydbm}{Generic interface to \code{dbm}-style databases.}
  45   \seemodule{whichdb}{Utility module used to determine the type of an
  46                       existing database.}
  47 \end{seealso}