[New-bugs-announce] [issue22577] local variable changes lost after pdb jump command

Xavier de Gaye report at bugs.python.org
Wed Oct 8 12:21:49 CEST 2014

New submission from Xavier de Gaye:

With the following pdb_jump.py script:

def foo(x):
    import pdb; pdb.set_trace()
    lineno = 3
    lineno = 4


The change made to 'x' is lost after a jump to line 4:

$ ./python ~/tmp/test/pdb_jump.py
> ~/tmp/test/pdb_jump.py(3)foo()
-> lineno = 3
(Pdb) x = 123
(Pdb) jump 4
> ~/tmp/test/pdb_jump.py(4)foo()
-> lineno = 4
(Pdb) x

The problem is that the Bdb format_stack_entry() method refers to frame.f_locals and thus overwrites the changes made to the f_locals dictionary as the f_locals dictionary is updated from the actual frame locals whenever the f_locals accessor is called as stated in a comment of the Pdb setup() method.

components: Library (Lib)
messages: 228783
nosy: georg.brandl, xdegaye
priority: normal
severity: normal
status: open
title: local variable changes lost after pdb jump command
type: behavior
versions: Python 3.4, Python 3.5

Python tracker <report at bugs.python.org>

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