# [issue8023] bug in s.append(x)

ughacks report at bugs.python.org
Fri Feb 26 09:55:32 CET 2010

```New submission from ughacks <ughacks at yahoo.com>:

Dear,

I am using
\$ python -V
Python 2.6.4
on Ubuntu 9.10

I met a serious bug in s.append(x) operation. If I append a list into another list, there is a change of content. In the following code, [2,-2,0,0] is replaced with [-2,-2,0,0] after s.append(x) operaton.

------- begin of code ------

total=[]
for i in range(4):
for j in range(i):
root=[0,0,0,0]
for k in [2,-2]:
for l in [2,-2]:
root[i]=k
root[j]=l
total.append(root)
print root
print total

--------------- end of code -----

Result: each element is correctly generated
[2, 2, 0, 0]
[-2, 2, 0, 0]
[2, -2, 0, 0]
[-2, -2, 0, 0]
[2, 0, 2, 0]
[-2, 0, 2, 0]
[2, 0, -2, 0]
[-2, 0, -2, 0]
[0, 2, 2, 0]
[0, -2, 2, 0]
[0, 2, -2, 0]
[0, -2, -2, 0]
[2, 0, 0, 2]
[-2, 0, 0, 2]
[2, 0, 0, -2]
[-2, 0, 0, -2]
[0, 2, 0, 2]
[0, -2, 0, 2]
[0, 2, 0, -2]
[0, -2, 0, -2]
[0, 0, 2, 2]
[0, 0, -2, 2]
[0, 0, 2, -2]
[0, 0, -2, -2]

But the total list is wrong
[[-2, -2, 0, 0], [-2, -2, 0, 0], [-2, -2, 0, 0], [-2, -2, 0, 0], [-2, 0, -2, 0], [-2, 0, -2, 0], [-2, 0, -2, 0], [-2, 0, -2, 0], [0, -2, -2, 0], [0, -2, -2, 0], [0, -2, -2, 0], [0, -2, -2, 0], [-2, 0, 0, -2], [-2, 0, 0, -2], [-2, 0, 0, -2], [-2, 0, 0, -2], [0, -2, 0, -2], [0, -2, 0, -2], [0, -2, 0, -2], [0, -2, 0, -2], [0, 0, -2, -2], [0, 0, -2, -2], [0, 0, -2, -2], [0, 0, -2, -2]]

----------
messages: 100141
nosy: ughacks
severity: normal
status: open
title: bug in s.append(x)
type: compile error
versions: Python 2.6

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue8023>
_______________________________________
```