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<H2><A NAME=
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To summarize the interface (
<code>key
</code> is a string,
<code>data
</code> is an
<div class=
"verbatim"><pre>
d = shelve.open(filename) # open -- file may get suffix added by low-level
d[key] = data # store data at key (overwrites old data if
data = d[key] # retrieve a COPY of data at key (raise KeyError if no
del d[key] # delete data stored at key (raises KeyError
flag = d.has_key(key) # true if the key exists
list = d.keys() # a list of all existing keys (slow!)
# as d was opened WITHOUT writeback=True, beware:
d['xx'] = range(
4) # this works as expected, but...
d['xx'].append(
5) # *this doesn't!* -- d['xx'] is STILL range(
4)!!!
# having opened d without writeback=True, you need to code carefully:
temp = d['xx'] # extracts the copy
temp.append(
5) # mutates the copy
d['xx'] = temp # stores the copy right back, to persist it
# or, d=shelve.open(filename,writeback=True) would let you just code
# d['xx'].append(
5) and have it work as expected, BUT it would also
# consume more memory and make the d.close() operation slower.
<p class=
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</p>
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<dt>Module
<b><tt class=
"module"><a href=
"module-anydbm.html">anydbm
</a></tt>:
</b>
<dd>Generic interface to
<code>dbm
</code>-style databases.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-bsddb.html">bsddb
</a></tt>:
</b>
<dd>BSD
<code>db
</code> database interface.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-dbhash.html">dbhash
</a></tt>:
</b>
<dd>Thin layer around the
<tt class=
"module">bsddb
</tt> which provides an
<tt class=
"function">open
</tt> function like the other database modules.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-dbm.html">dbm
</a></tt>:
</b>
<dd>Standard
<span class=
"Unix">Unix
</span> database interface.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-dumbdbm.html">dumbdbm
</a></tt>:
</b>
<dd>Portable implementation of the
<code>dbm
</code> interface.
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"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-gdbm.html">gdbm
</a></tt>:
</b>
<dd>GNU database interface, based on the
<code>dbm
</code> interface.
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"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-pickle.html">pickle
</a></tt>:
</b>
<dd>Object serialization used by
<tt class=
"module">shelve
</tt>.
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<dt>Module
<b><tt class=
"module"><a href=
"module-cPickle.html">cPickle
</a></tt>:
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<dd>High-performance version of
<tt class=
"module"><a href=
"module-pickle.html">pickle
</a></tt>.
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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