List comprehension scope error from Python debugger

Question

In debugging my code, I want to use a list comprehension. However, it seems I cannot evaluate a list comprehension from the debugger when I\'m inside a function.

I a

Answer 1

In Python 3, you have to use the interact command in pdb before you can access any non-global variables due to a change in the way comprehensions are implemented.

>>> def foo(): [][0]
... 
>>> foo()
Traceback (most recent call last):
  File "", line 1, in 
  File "", line 1, in foo
IndexError: list index out of range
>>> import pdb;pdb.pm()
> (1)foo()
(Pdb) x = 4
(Pdb) [x for _ in range(2)]
*** NameError: name 'x' is not defined
(Pdb) interact
*interactive*
>>> [x for _ in range(2)]
[4, 4]
>>>