On Thursday, 3 November 2022 09:48:49 PDT Marc Mutz via Development wrote: > Hi Thiago, > > On 03.11.22 16:17, Thiago Macieira wrote: > > the devil will be in the details because of QT_REMOVED_SINCE. > > What, specifically, are you thinking about here? For the sketched > approach to work, no new relational operator must be exported, because > we need to keep BC between C++17 and C++20 builds. If existing ones are, > we'll need to QT_REMOVED_SINCE them. Where's the problem?
Nothing specific. It could be nothing, it could be simple ugliness that / code readability, or there may be some classes we can't move the operators away for at all: there was one case we couldn't remove / move away because the method was inline and was used by QtCore itself. We won't know until we try. > > For some classes, we could postpone changing anything until C++20 is > > required. > You lost me there. Why do you think so? Because of the sentence above? > Requiring C++20 won't be a BC break, so we'd still have all the old > exported relational operators to QT_REMOVED_SINCE. A simple question of code readability. If it's not that important and it makes the code significantly uglier, we can simply postpone until it's not ugly. > > Meanwhile, we have qcompare.h. > > Here, too, I feel lost. I'm struggling to see what a NIH > std::partial_ordering w/o the weak and strong counterparts and w/o op<=> > language support could achieve, except another vocabulary type mismatch. > Can you elaborate? We can use it until we can depend on C++20. Like QSpan, that's why it's there. Or the methods can simply return int, like I intended in QCborValue. > Meanwhile, in a Jira comment, Eddy discovered a potential problem with > partial_ordering::unordered: we have a lot of types that have > std::optional folded into them (isNull/isValid) and, if they're ordered, > they need to have decided on a total order, ie. incl. for invalid/null > ones (QDateTime sorts invalid before valid e.g.). These types' op<=> > could now return unordered for invalid values, but that would change the > semantics of the op< derived from it vis a vis the existing op<. What's the recommendation? Create a total order where null < empty < any non- empty, or use partial ordering? -- Thiago Macieira - thiago.macieira (AT) intel.com Cloud Software Architect - Intel DCAI Cloud Engineering _______________________________________________ Development mailing list Development@qt-project.org https://lists.qt-project.org/listinfo/development
