A ``shelf'' is a persistent, dictionary-like object. The difference with ``dbm'' databases is that the values (not the keys!) in a shelf can be essentially arbitrary Python objects -- anything that the pickle module can handle. This includes most class instances, recursive data types, and objects containing lots of shared sub-objects. The keys are ordinary strings.
To summarize the interface (key
is a string, data
is an
arbitrary object):
import shelve d = shelve.open(filename) # open, with (g)dbm filename -- no suffix d[key] = data # store data at key (overwrites old data if # using an existing key) data = d[key] # retrieve data at key (raise KeyError if no # such key) del d[key] # delete data stored at key (raises KeyError # if no such key) flag = d.has_key(key) # true if the key exists list = d.keys() # a list of all existing keys (slow!) d.close() # close it
Restrictions:
See Also:
dbm
-style databases.
db
database interface.
dbm
interface.
dbm
interface.
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