See following example:
$ cat -n foo.py
1 def func():
2 v = another_func()
3 print v
4
5 func()
$ pdb foo.py
> /root/tmp/foo.py(1)<module>()
-> def func():
(Pdb) break 2
Breakpoint 1 at /root/tmp/foo.py:2
(Pdb) cont
> /root/tmp/foo.py(2)func()
-> v = another_func()
(Pdb) v = 123 <-- manually create the var
(Pdb) jump 3 <-- skip another_func()
> /root/tmp/foo.py(3)func()
-> print v
(Pdb) next
UnboundLocalError: "local variable 'v' referenced before assignment"
> /root/tmp/foo.py(3)func()
-> print v
(Pdb)
Where is the var v
if it's not created in the func()
?
This is a pdb bug, where changes to local variables are lost after a jump. It was reported years ago, but it never got fixed.