Pdb NameError in generator param and list comprehension #80052

Activity

1. jayanth commented on Feb 1, 2019

   

   jayanthmannequin

   on Feb 1, 2019

   MannequinAuthor

   More actions

   I get a NameError for a variable in the generator param of a function or in a list comprehension. See example below. The variable is available to the program, but not to the interactive Pdb shell.

   # Test file:

   def main(nn=10):
       xx = list(range(nn))
       breakpoint()
       for ii in range(nn):
           num = sum(xx[jj] for jj in range(nn))
       print(f'xx={xx}')
   
   if __name__ == '__main__':
       main()

   $ python3
   Python 3.7.2 (default, Jan 13 2019, 12:50:15)
   [Clang 10.0.0 (clang-1000.11.45.5)] on darwin
   Type "help", "copyright", "credits" or "license" for more information.

   >>

   $ python3 /tmp/test.py
   > /tmp/test.py(5)main()
   -> for ii in range(nn):
   (Pdb) n
   > /tmp/test.py(6)main()
   -> num = sum(xx[jj] for jj in range(nn))
   (Pdb) sum(xx[jj] for jj in range(nn))
   *** NameError: name 'xx' is not defined
   (Pdb) [xx[jj] for jj in range(nn)]
   *** NameError: name 'xx' is not defined
   (Pdb) c
   xx=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

   FWIW python3 is a homebrew installation. I had the same issue with 3.7.0 as well (also homebrew):
   Python 3.7.0 (default, Sep 18 2018, 18:47:22)
   [Clang 9.1.0 (clang-902.0.39.2)] on darwin
2. jayanth

   added

   3.7 (EOL)end of lifeend of life

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Feb 1, 2019
3. tirkarthi commented on Feb 1, 2019

   

   tirkarthi

   on Feb 1, 2019

   Member

   More actions

   Thanks for the report. This seems related to bpo-21161 and bpo-26072 that contain explanation about scope where exec is called with the code and patches that fix this issue. As a possible workaround in the issues you can use "interact" command to get to a REPL where you can evaluate and exit back to pdb.
4. jayanth commented on Feb 1, 2019

   

   jayanthmannequin

   on Feb 1, 2019

   MannequinAuthor

   More actions

   Thanks for the "interact" tip.

   FWIW, I see this issue in 2.7.10 as well. Although the list comprehension works.

   $ python
   Python 2.7.10 (default, Oct  6 2017, 22:29:07)
   [GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)] on darwin
   Type "help", "copyright", "credits" or "license" for more information.
   >>> ^D

   $ python /tmp/test2.py
   > /tmp/test2.py(5)main()
   -> for ii in range(nn):
   (Pdb) n
   > /tmp/test2.py(6)main()
   -> num = sum(xx[jj] for jj in range(nn))
   (Pdb) sum(xx[jj] for jj in range(nn))
   *** NameError: global name 'xx' is not defined
   (Pdb) [xx[jj] for jj in range(nn)]
   [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
   (Pdb) c
   ('xx', [0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

   # test2.py

   def main(nn=10):
       xx = list(range(nn))
       import pdb; pdb.set_trace()
       for ii in range(nn):
           num = sum(xx[jj] for jj in range(nn))
       print('xx', xx)
   
   if __name__ == '__main__':
       main()
5. ezio-melotti

   transferred this issue fromon Apr 10, 2022
6. gaogaotiantian commented on May 6, 2024

   

   gaogaotiantian

   on May 6, 2024

   Member

   More actions

   Fix by PEP 709 + #111094
7. gaogaotiantian

   closed this as completedon May 6, 2024