[Python-Dev] Policy for making changes to the AST (original) (raw)

Benjamin Peterson benjamin at python.org
Thu Apr 7 23:56:52 CEST 2011

2011/4/7 Maciej Fijalkowski <fijall at gmail.com>:

AFAIK the AST is CPython-specific so should be treated with the same attitude as changes to the bytecode. That means, do it conservatively, since there are people who like to write tools that manipulate or analyze this, and while they know they're doing something CPython and version-specific, they should not be broken by bugfix releases, since the people who use their code probably have no idea of the deep magic they're depending on. PyPy implements exactly the same AST. I think Jython also does, although I'm not that sure. There were already issues with say subclassing ast nodes were pypy was incompatible from CPython. That said, it's completely fine from PyPy's perspective to change AST between major releases.

Speaking as the author of PyPy's AST implementation, there are even some changes I'd like to make it easier!

-- Regards, Benjamin

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