How do I manipulate a variable whose name conflicts with PDB commands?

Question

My code is, for better or worse, rife with single letter variables (it's physics stuff, so those letters are meaningful), as well as NumPy's, which I'm often interacting with.

When using the Python debugger, occasionally I'll want to look at the value of, say, n. However, when I hit n<enter>, that's the PDB command for (n)ext, which has a higher priority. print n works around looking at it, but how can I set it?

Answer 1

Use an exclamation mark ! before a statement to have it run :

python -m pdb test.py
> /home/user/test.py(1)<module>()
-> print('foo')
(Pdb) !n = 77
(Pdb) !n
77
(Pdb) n
foo
> /home/user/test.py(2)<module>()
-> print('bar')
(Pdb)

The docs say:

! statement

Execute the (one-line) statement in the context of the current stack frame. The exclamation point can be omitted unless the first word of the statement resembles a debugger command. [...]

Answer 2

You can use semicolons, so just put something else in front of it:

ipdb> print n
2
ipdb> n
> 145 <some code here>
  146
  147

ipdb> 1; n=4
1
ipdb> print n
4

Answer 3

That is not the direct answer to your question, but it may help you: PuDB is a console-based visual interface for PDB which separates commands from variable manipulation by design.

Answer 4

Eric IDE, Wing IDE & Spyder to mention just a few all have visual debuggers that are worth a go as they separate the display of values from the commands.

Answer 5

The solution is quite simple! Just to use brackets (variable_name).

For example, if you have one vairable named q, you want to check out it value, if you directly input q in the prompt, then the ipdb debugging process will quit and break up.

>>> q

Instead, you should input (q) to ckeck this vairable:

>>> (q)

Then its value will be printed.