Very happy to hear it. It's almost like you were present at the sprint! On Fri, Sep 9, 2016 at 7:04 PM, Eric V. Smith <e...@trueblade.com> wrote: > I found some time before beta 1 to modify the f-string code to implement the > desired behavior: no backslashes inside the curly braces, but they're > allowed in the literal string portions. I just checked it in. > > I still need to update PEP 498, and the documentation needs updating. I'll > create an issue for the docs once I've updated the PEP. > > This is a fairly large change, because now I need to parse the f-strings in > UTF-8, and do the decoding myself in pieces, instead of the previous > behavior of decoding the string first and then parsing it. > > I think I have tests for all of the backslash scenarios, but I'll watch the > buildbots. > > Eric. > > > On 8/30/2016 1:55 PM, Eric V. Smith wrote: >> >> After a long discussion on python-ideas (starting at >> https://mail.python.org/pipermail/python-ideas/2016-August/041727.html) >> I'm proposing the following change to PEP 498: backslashes inside >> brackets will be disallowed. The point of this is to disallow convoluted >> code like: >> >>>>> d = {'a': 4} >>>>> f'{d[\'a\']}' >> >> '4' >> >> In addition, I'll disallow escapes to be used for brackets, as in: >> >>>>> f'\x7bd["a"]}' >> >> '4' >> >> (where chr(0x7b) == "{"). >> >> Because we're so close to 3.6 beta 1, my plan is to: >> >> 1. Modify the PEP to reflect these restrictions. >> 2. Modify the code to prevent _any_ backslashes inside f-strings. >> >> This is a more restrictive change than the PEP will describe, but it's >> much easier to implement. After beta 1, and hopefully before beta 2, I >> will implement the restrictions as I've outlined above (and as they will >> be documented in the PEP). The net effects are: >> >> a. Some code that works in the alphas won't work in beta 1. I'll >> document this. >> b. All code that's valid in beta 1 will work in beta 2, and some >> f-strings that are syntax errors in beta 1 will work in beta 2. >> >> I've discussed this issue with Ned and Guido, who are okay with these >> changes. >> >> The python-ideas thread I referenced above has some discussion about >> further changes to f-strings. Those proposals are outside the scope of >> 3.6, but the changes I'm putting forth here will allow for those >> additional changes, should we decide to make them. That's a discussion >> for 3.7, however. >> >> I'm sending this email out just to notify people of this upcoming >> change. I hope this won't generate much discussion. If you feel the need >> to discuss this issue further, please use the python-ideas thread (where >> some people are already ignoring it!). >> >> Eric. >> _______________________________________________ >> Python-Dev mailing list >> Python-Dev@python.org >> https://mail.python.org/mailman/listinfo/python-dev >> Unsubscribe: >> https://mail.python.org/mailman/options/python-dev/eric%2Ba-python-dev%40trueblade.com >> > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org
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