My preference is (1), revert. You have to understand how sys.modules works before you can change it, and if you waste time debugging your mistake, so be it. I think the sys.py proposal is the wrong way to fix the mistake you made there.
On Wed, Sep 13, 2017 at 4:00 PM, Eric Snow <ericsnowcurren...@gmail.com> wrote: > On Tue, Sep 12, 2017 at 9:30 PM, Guido van Rossum <gu...@python.org> > wrote: > > I find this a disturbing trend. > > Which trend? Moving away from "consenting adults"? In the case of > sys.modules, the problem is that assigning a bogus value (e.g. []) can > cause the interpreter to crash. It wasn't a problem until recently > when I removed PyInterpreterState.modules and made sys.modules > authoritative (see https://bugs.python.org/issue28411). The options > there are: > > 1. revert that change (which means assigning to sys.modules > deceptively does nothing) > 2. raise an exception in all the places that expect sys.modules to be > a mapping (far from where sys.modules was re-assigned) > 3. raise an exception if you try to set sys.modules to a non-mapping > 4. let a bogus sys.modules break the interpreter (basically, tell > people "don't do that") > > My preference is #3 (obviously), but it sounds like you'd rather not. > > > I think we have bigger fish to fry and this sounds like it could slow > down startup. > > It should have little impact on startup. The difference is the cost > of importing the new sys module (which we could easily freeze to > reduce the cost). That cost would apply only to programs that > currently import sys. Everything in the stdlib would be updated to > use _sys directly. > > If you think it isn't worth it then I'll let it go. I brought it up > because I consider it a cheap, practical solution to the problem I ran > into. Thanks! > > -eric > -- --Guido van Rossum (python.org/~guido)
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