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

Guido van Rossum guido at python.org
Mon Apr 4 22:31:40 CEST 2011

On Mon, Apr 4, 2011 at 12:56 PM, Terry Reedy <tjreedy at udel.edu> wrote:

Moving optimizations from bytecode (where they are demonstrably a bit fragile) to ast manipulations (where we presume they will be more robust and can be broader) should be a win in itself

I am still doubtful of that. While in theory it is easier to become confused about what the bytecode means, in practice the bugs we had due to bytecode optimization were based on misunderstandings and unintended consequences that would have caused the exact same bug if the optimization was done at the AST level. (E.g. various mistreatments of -0, ignoring possible floating point misbehavior for extreme values or situations.)

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

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