Ezio Melotti added the comment:
That's because with [{}] * 3 you get a list with 3 copies of the same object,
so all the elements in c refer to the same dict:
>>> a = [{}, {}, {}]
>>> b = [{}] + [{}] + [{}]
>>> c = [{}] * 3
>>> map(id, a)
[12850496, 12850784, 12850928]
>>> map(id, b)
[12851648,
New submission from muzuiget :
platform: ubuntu 10.04 amd64, python 2.6.5 r265:79063
run below code
a = [{}, {}, {}]
b = [{}] + [{}] + [{}]
c = [{}] * 3
print a, len(a), type(a)
print b, len(b), type(b)
print c, len(c), type(c)
a[1]["test"] = 1234
b[1]["test"] = 1234
c[1]["test"] = 1234
print
