diff options
Diffstat (limited to 'Doc/lib/libshelve.tex')
| -rw-r--r-- | Doc/lib/libshelve.tex | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/Doc/lib/libshelve.tex b/Doc/lib/libshelve.tex index 1e02c7b..e8491be 100644 --- a/Doc/lib/libshelve.tex +++ b/Doc/lib/libshelve.tex @@ -19,7 +19,8 @@ arbitrary object): \begin{verbatim} import shelve -d = shelve.open(filename) # open, with (g)dbm filename -- no suffix +d = shelve.open(filename) # open -- file may get suffix added by low-level + # library d[key] = data # store data at key (overwrites old data if # using an existing key) @@ -54,8 +55,10 @@ cause the database to refuse updates. \refbimodindex{gdbm} \item -Dependent on the implementation, closing a persistent dictionary may -or may not be necessary to flush changes to disk. +Depending on the implementation, closing a persistent dictionary may +or may not be necessary to flush changes to disk. The \method{__del__} +method of the \class{Shelf} class calls the \method{close} method, so the +programmer generally need not do this explicitly. \item The \module{shelve} module does not support \emph{concurrent} read/write @@ -67,10 +70,37 @@ requires knowledge about the database implementation used. \end{itemize} +\begin{classdesc}{Shelf}{dict\optional{, binary=False}} +A subclass of \class{UserDict.DictMixin} which stores pickled values in the +\var{dict} object. If the \var{binary} parameter is \constant{True}, binary +pickles will be used. This can provide much more compact storage than plain +text pickles, depending on the nature of the objects stored in the databse. +\end{classdesc} + +\begin{classdesc}{BsdDbShelf}{dict\optional{, binary=False}} +A subclass of \class{Shelf} which exposes \method{first}, \method{next}, +{}\method{previous}, \method{last} and \method{set_location} which are +available in the \module{bsddb} module but not in other database modules. +The \var{dict} object passed to the constructor must support those methods. +This is generally accomplished by calling one of \function{bsddb.hashopen}, +\function{bsddb.btopen} or \function{bsddb.rnopen}. The optional +\var{binary} parameter has the same interpretation as for the \class{Shelf} +class. +\end{classdesc} + +\begin{classdesc}{DbfilenameShelf}{dict\optional{, flag='c'}\optional{, binary=False}} +A subclass of \class{Shelf} which accepts a filename instead of a dict-like +object. The underlying file will be opened using \function{anydbm.open}. +By default, the file will be created and opened for both read and write. +The optional \var{binary} parameter has the same interpretation as for the +\class{Shelf} class. +\end{classdesc} \begin{seealso} \seemodule{anydbm}{Generic interface to \code{dbm}-style databases.} - \seemodule{dbhash}{BSD \code{db} database interface.} + \seemodule{bsddb}{BSD \code{db} database interface.} + \seemodule{dbhash}{Thin layer around the \module{bsddb} which provides an + \function{open} function like the other database modules.} \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.} |