Message 132453 - Python tracker

➜

This issue tracker has been migrated to GitHub, and is currently read-only.
For more information, see the GitHub FAQs in the Python's Developer Guide.

Content 
If we have to preserve backward compatibility of Python AST API, we can do this relatively easily (at the expense of some code complexity):
* Add 'version' argument to compile() and ast.parse() with default value of 1 (old AST). Value 2 will correspond to the new AST.
* Do not remove Num/Str/Bytes/Ellipsis Python classes. Make PyAST_obj2mod and PyAST_mod2obj do appropriate conversions when version is 1.
* Possibly emit a PendingDeprecationWarning when version 1 is used with the goal of removing it in 3.5

Alternative implementation is to leave Num/Str/etc classes in C as well, and write visitors (similar to folding one) to convert AST between old and new forms.

Does this sounds reasonable? Should this be posted to python-dev? Should I write a PEP (I'd need some help with this)?

Are there any other big issues preventing this to be merged?