Use 4 spaces for indentation in PDB

[treyhunner]

Feature or enhancement

Proposal:

It looks like PDB evolved the ability to handle multi-line Python expressions in Python 3.13. I didn't see this mentioned in the release notes, but I'm excited to see this feature. Thank you to whoever added this feature! (@gaogaotiantian maybe?)

I did notice that the Tab key works in a somewhat unexpected way.

When I hit Enter at the end of an if True: line, I see:

Then if I hit the Tab key I see this:

Note that a tab character is inserted (just as one would be within the old Python REPL) but the tab width looks like 2 spaces.

I expected to see this instead:

In the old Python REPL, the Tab key used to insert a tab character, but it looked like 4 spaces were inserted because the tab stop happened to be 4 characters from the end of the >>> prompt (which is 4 characters long):

One way to resolve this would be to shorten the PDB prompt to something like (P) or PDB .

I would propose instead that the Tab key should insert 4 spaces in PDB (just as the new REPL does).

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-125377: Improve tab indentation for pdb multi-line input #130471

[savannahostrowski]

@gaogaotiantian for input

[hacscred]

Is there any reason for not just interpreting TAB as N spaces with N having some default configurable somewhere for those people with control issues?

[gaogaotiantian]

Thanks for raising this up. This is implemented in #130471 .