python_shallow_copy.py

a = set([hashabledict({1:11}), hashabledict({2:22})])
b = set([hashabledict({1:11}), hashabledict({3:33})])
for i in range(3):
    print "set a:", a, id(a)
    copyofa = set(a)
    print "shallow copy ofset a:", copyofa, id(copyofa)
    delta = copyofa-b
    print "delta", delta
    for item in delta:
        print id(item)
        item[1] = "xx"
    print "*"*10

#--------------result-----------------
#set a: set([{1: 11}, {2: 22}]) 70757112
#shallow copy ofset a: set([{1: 11}, {2: 22}]) 72005912
#delta set([{2: 22}])
#72099360
#**********
#set a: set([{1: 11}, {1: 'xx', 2: 22}]) 70757112
#shallow copy ofset a: set([{1: 11}, {1: 'xx', 2: 22}]) 72004472
#delta set([{1: 'xx', 2: 22}])
#72099360
#**********
#set a: set([{1: 11}, {1: 'xx', 2: 22}]) 70757112
#shallow copy ofset a: set([{1: 11}, {1: 'xx', 2: 22}]) 72006032
#delta set([{1: 'xx', 2: 22}])
#72099360