adii1823
41 lines
995 B
Python
41 lines
995 B
Python
# persistence/shelf.py
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import shelve
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class Person:
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def __init__(self, name, id):
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self.name = name
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self.id = id
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with shelve.open('shelf1.shelve') as db:
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db['obi1'] = Person('Obi-Wan', 123)
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db['ani'] = Person('Anakin', 456)
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db['a_list'] = [2, 3, 5]
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db['delete_me'] = 'we will have to delete this one...'
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print(list(db.keys())) # ['ani', 'delete_me', 'a_list', 'obi1']
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del db['delete_me'] # gone!
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print(list(db.keys())) # ['ani', 'a_list', 'obi1']
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print('delete_me' in db) # False
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print('ani' in db) # True
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a_list = db['a_list']
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a_list.append(7)
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db['a_list'] = a_list
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print(db['a_list']) # [2, 3, 5, 7]
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# this way allows writeback:
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# working with lists is easier, but consumes more memory and
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# closing the file takes longer.
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with shelve.open('shelf2.shelve', writeback=True) as db:
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db['a_list'] = [11, 13, 17]
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db['a_list'].append(19) # in-place append!
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print(db['a_list']) # [11, 13, 17, 19]
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