[Python-Dev] [compatibility-sig] do all VMs implement the ast module? (was: Re: AST optimizer implemented in Python) (original) (raw)

Guido van Rossum guido at python.org
Mon Aug 13 22:46:09 CEST 2012

On Mon, Aug 13, 2012 at 1:05 PM, fwierzbicki at gmail.com <fwierzbicki at gmail.com> wrote:

On Mon, Aug 13, 2012 at 12:06 PM, Brett Cannon <brett at python.org> wrote:

I see nothing about ast possibly being CPython only. Should there be?

Time to ask the other VMs what they are currently doing (the ast module came into existence in Python 2.6 so all the VMs should be answer the question since Jython is in alpha for 2.7 compatibility).

[Jython]

2.5+ contains an ast.py that I obsessively compared to CPython's 2.5 ast.py.

But CPython's ast.py contains very little code -- it's all done in ast.c.

Still, I'm glad you are actually considering this a cross-language feature, and I will gladly retract my warning. (Still, I don't know if it is subject to the usual backward compatibility constraints.)

I haven't applied the same obsessiveness to 2.7, but I do intend to look closely at Jython's ast.py results compared to CPython's in the 3.x effort. Also I plan to allow some backwards compatibility compromises between early point releases of our 2.7 series, as I want to apply what I learn in our 3.x effort to 2.7 point releases, so we should be able to keep up with most simple ast.py changes. I'm not so sure that the current discussion are going to be "simple though" :) -- if it's pure python we should hopefully be alright.

It might be pure python for Jython, but it's not for CPython.

-- --Guido van Rossum (python.org/~guido)

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