cpython/Demo/classes/Dbm.py

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1992-08-13 09:14:11 -03:00
# A wrapper around the (optional) built-in class dbm, supporting keys
# and values of almost any type instead of just string.
# (Actually, this works only for keys and values that can be read back
# correctly after being converted to a string.)
class Dbm:
def __init__(self, filename, mode, perm):
import dbm
self.db = dbm.open(filename, mode, perm)
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def __repr__(self):
s = ''
for key in self.keys():
t = repr(key) + ': ' + repr(self[key])
if s: t = ', ' + t
s = s + t
return '{' + s + '}'
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def __len__(self):
return len(self.db)
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def __getitem__(self, key):
return eval(self.db[repr(key)])
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def __setitem__(self, key, value):
self.db[repr(key)] = repr(value)
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def __delitem__(self, key):
del self.db[repr(key)]
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def keys(self):
res = []
for key in self.db.keys():
res.append(eval(key))
return res
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def has_key(self, key):
return self.db.has_key(repr(key))
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def test():
d = Dbm('@dbm', 'rw', 0600)
print d
while 1:
try:
key = input('key: ')
if d.has_key(key):
value = d[key]
print 'currently:', value
value = input('value: ')
if value is None:
del d[key]
else:
d[key] = value
except KeyboardInterrupt:
print ''
print d
except EOFError:
print '[eof]'
break
print d
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test()