On Sat, Sep 10, 2016 at 10:04:46AM +1000, Damien George wrote: > I guess my main question to this list is: if CPython were to add a > function to change the optimisation level at runtime, what would it > look like?
I don't think it would look like sys.optimize(flag). At the very least, it would have to take *at least* three values: - no optimizations (the default) - remove asserts (-O) - remove asserts and docstrings (-OO) but even that is very limiting. Why can't I keep asserts, which may be useful and important in running code, but remove docstrings, which mostly are used interactively? I think the idea of "optimization levels" has reached its use-by date and we should start considering separate flags for each individual optimization. In particular, I expect that some time soon somebody will propose at least one more optimization: - remove annotations and I seem to recall somebody requesting the ability to turn off constant folding, although I don't remember why. I can easily imagine Python implementations offering flags to control more complex/risky optimizations: - resolve built-in names at compile-time[1] - inline small functions - unroll loops etc. Victor Stinner is (I think) working on bringing some of these to CPython, and it seems to me that if they are to be under any user-control at all, a simple optimization level counter is not going to be sufficient. We're going to need a set of flags. But it seems to me that the ability to change optimizations at runtime would be rather confusing. Shouldn't optimizations, or at least some of them, apply on a per-module basis rather than globally? I don't even know how to reason about code optimizations if any function I run might have changed the optimization level without my knowledge. So I think this is a very dubious idea. [1] Yes, I know that will change the semantics of Python code. -- Steve _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
