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svn+ssh://pythondev@svn.python.org/python/branches/p3yk ........ r55077 | guido.van.rossum | 2007-05-02 11:54:37 -0700 (Wed, 02 May 2007) | 2 lines Use the new print syntax, at least. ........ r55142 | fred.drake | 2007-05-04 21:27:30 -0700 (Fri, 04 May 2007) | 1 line remove old cruftiness ........ r55143 | fred.drake | 2007-05-04 21:52:16 -0700 (Fri, 04 May 2007) | 1 line make this work with the new Python ........ r55162 | neal.norwitz | 2007-05-06 22:29:18 -0700 (Sun, 06 May 2007) | 1 line Get asdl code gen working with Python 2.3. Should continue to work with 3.0 ........ r55164 | neal.norwitz | 2007-05-07 00:00:38 -0700 (Mon, 07 May 2007) | 1 line Verify checkins to p3yk (sic) branch go to 3000 list. ........ r55166 | neal.norwitz | 2007-05-07 00:12:35 -0700 (Mon, 07 May 2007) | 1 line Fix this test so it runs again by importing warnings_test properly. ........ r55167 | neal.norwitz | 2007-05-07 01:03:22 -0700 (Mon, 07 May 2007) | 8 lines So long xrange. range() now supports values that are outside -sys.maxint to sys.maxint. floats raise a TypeError. This has been sitting for a long time. It probably has some problems and needs cleanup. Objects/rangeobject.c now uses 4-space indents since it is almost completely new. ........ r55171 | guido.van.rossum | 2007-05-07 10:21:26 -0700 (Mon, 07 May 2007) | 4 lines Fix two tests that were previously depending on significant spaces at the end of a line (and before that on Python 2.x print behavior that has no exact equivalent in 3.0). ........
89 lines
3.2 KiB
TeX
89 lines
3.2 KiB
TeX
\section{\module{dbhash} ---
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DBM-style interface to the BSD database library}
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\declaremodule{standard}{dbhash}
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\modulesynopsis{DBM-style interface to the BSD database library.}
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\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
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The \module{dbhash} module provides a function to open databases using
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the BSD \code{db} library. This module mirrors the interface of the
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other Python database modules that provide access to DBM-style
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databases. The \refmodule{bsddb}\refbimodindex{bsddb} module is required
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to use \module{dbhash}.
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This module provides an exception and a function:
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\begin{excdesc}{error}
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Exception raised on database errors other than
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\exception{KeyError}. It is a synonym for \exception{bsddb.error}.
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\end{excdesc}
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\begin{funcdesc}{open}{path\optional{, flag\optional{, mode}}}
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Open a \code{db} database and return the database object. The
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\var{path} argument is the name of the database file.
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The \var{flag} argument can be
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\code{'r'} (the default), \code{'w'},
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\code{'c'} (which creates the database if it doesn't exist), or
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\code{'n'} (which always creates a new empty database).
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For platforms on which the BSD \code{db} library supports locking,
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an \character{l} can be appended to indicate that locking should be
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used.
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The optional \var{mode} parameter is used to indicate the \UNIX{}
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permission bits that should be set if a new database must be
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created; this will be masked by the current umask value for the
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process.
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\end{funcdesc}
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\begin{seealso}
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\seemodule{anydbm}{Generic interface to \code{dbm}-style databases.}
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\seemodule{bsddb}{Lower-level interface to the BSD \code{db} library.}
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\seemodule{whichdb}{Utility module used to determine the type of an
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existing database.}
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\end{seealso}
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\subsection{Database Objects \label{dbhash-objects}}
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The database objects returned by \function{open()} provide the methods
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common to all the DBM-style databases and mapping objects. The following
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methods are available in addition to the standard methods.
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\begin{methoddesc}[dbhash]{first}{}
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It's possible to loop over every key/value pair in the database using
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this method and the \method{next()} method. The traversal is ordered by
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the databases internal hash values, and won't be sorted by the key
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values. This method returns the starting key.
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\end{methoddesc}
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\begin{methoddesc}[dbhash]{last}{}
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Return the last key/value pair in a database traversal. This may be used to
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begin a reverse-order traversal; see \method{previous()}.
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\end{methoddesc}
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\begin{methoddesc}[dbhash]{next}{}
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Returns the key next key/value pair in a database traversal. The
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following code prints every key in the database \code{db}, without
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having to create a list in memory that contains them all:
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\begin{verbatim}
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print db.first()
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for i in range(1, len(db)):
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print db.next()
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\end{verbatim}
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\end{methoddesc}
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\begin{methoddesc}[dbhash]{previous}{}
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Returns the previous key/value pair in a forward-traversal of the database.
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In conjunction with \method{last()}, this may be used to implement
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a reverse-order traversal.
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\end{methoddesc}
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\begin{methoddesc}[dbhash]{sync}{}
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This method forces any unwritten data to be written to the disk.
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\end{methoddesc}
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