Description

hukkin

opened on Oct 30, 2024

Issue body actions

Feature or enhancement

Proposal:

Add the same attributes to tomllib.TOMLDecodeError that json.JSONDecodeError also has, namely: msg, doc, pos, lineno, colno. This will help user facing apps show customized errors to users.

This draft PR in Tomli shows the proposed changes.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/69546

Linked PRs

• gh-126175: Add attributes to TOMLDecodeError. Deprecate free-form __init__ args #126428

Activity

1. hukkin

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on Oct 30, 2024
2. hukkin commented on Oct 30, 2024

   

   hukkin

   on Oct 30, 2024

   ContributorAuthor

   More actions

   Pinging codeowners @hauntsaninja and @encukou

   Thoughts on my concern in Discourse about the change breaking TOMLDecodeError init with no arguments would be much appreciated:

   Unfortunately, this changes signature of TOMLDecodeError so breaks any users instantiating the error. Not sure why anyone would do that though? Some less breaking options are using keyword arguments, or dynamically injecting attributes after instantiation.
3. nineteendo commented on Oct 30, 2024

   

   nineteendo

   on Oct 30, 2024

   Contributor

   More actions

   I would use keywords arguments defaulting to None. Also see PEP-387.

   Reacted by Petr Viktorin, Taneli Hukkinen and Bénédikt Tran
4. picnixz

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on Oct 30, 2024
5. picnixz commented on Oct 30, 2024

   

   picnixz

   on Oct 30, 2024

   Member

   More actions

   Unfortunately, this changes signature of TOMLDecodeError so breaks any users instantiating the error. Not sure why anyone would do that though? Some less breaking options are using keyword arguments, or dynamically injecting attributes after instantiation.

   You can instantiate those errors if you create a custom tomllib extension (e.g., to handle extended syntax not supported by TOML but you still want to use the same exceptions for that).

   I would use keywords arguments defaulting to None

   Agreed.
6. hukkin commented on Oct 30, 2024

   

   hukkin

   on Oct 30, 2024

   ContributorAuthor

   More actions

   Thanks all for the feedback! I've updated my PoC draft PR in Tomli to be fully backwards compatible. It also adds a deprecation warning for use of positional arguments, which is simple to remove if folks think it's unnecessary. With it I think we could eventually move to the same exact signature that json.JSONDecodeError has.
7. encukou

   added a commit that references this issue on Nov 13, 2024

   gh-126175: Add attributes to TOMLDecodeError. Deprecate free-form `__…

   29b5323
8. encukou

   closed this as completedon Nov 13, 2024
9. picnixz

   added a commit that references this issue on Dec 8, 2024

   pythongh-126175: Add attributes to TOMLDecodeError. Deprecate free-fo…

   ae19768
10. ebonnal

    added a commit that references this issue on Jan 12, 2025

    pythongh-126175: Add attributes to TOMLDecodeError. Deprecate free-fo…

    3b3fc2f

Issue actions