pdb: "var = value" 没有在当前函数中创建 var?

pdb: "var = value" did not create the var in current function?

参见以下示例:

[STEP 103] # cat -n foo.py
     1  def func():
     2      v = another_func()
     3      print v
     4
     5  func()
[STEP 104] # 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)

如果 var v 不是在 func() 中创建的,它在哪里?

这是一个pdb bug,其中对局部变量的更改在跳转后丢失。几年前就有报道,但一直没有修复。