Hello,
while trying to learn how to program using objects in python (up to now
simple scripts were sufficient for my needs) I stumbled over the
a problem while assigning values to an object.
The following piece of code shows what I intend to do:
<---snip--->
class new_class(object):
def __init__( self,
internal_list=[]):
self.internal_list= internal_list
external_list=[[b*a for b in xrange(1,5)] for a in xrange(1,5)]
print external_list
first_collection=[new_class() for i in xrange(4)]
temporary_list=[[] for i in xrange(4)]
for i in xrange(4):
for j in xrange(4):
temporary_list[i].append(external_list[i][j])
first_collection[i].internal_list=temporary_list[i]
#Now everything is as I want it to be:
for i in xrange(4):
print first_collection[i].internal_list
#Now I tried to get the same result without the temporary
#variable:
second_collection=[new_class() for i in xrange(4)]
for i in xrange(4):
for j in xrange(4):
second_collection[i].internal_list.append(external_list[i][j])
#Which obviously leads to a very different result:
for i in xrange(4):
print second_collection[i].internal_list
<---snip--->
Can someone explain to me, what's happening here and why the two
approaches do not lead to the same results? Thanks in Advance.
Regards,
Manuel
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