On 25 September 2016 at 10:38, Giuseppe D'Angelo <giuseppe.dang...@kdab.com> wrote: > Hi, > > Il 24/09/2016 02:50, Ch'Gans ha scritto: >> Adding my 2 cents, I haven't use QDataStream stream much, yet i'm very >> well aware of this restriction. I think the documentation is very >> explicit about this. And that might be the reason i haven't use it >> much. > > I'm actually arguing that there's no such restriction. The format used > on the wire is documented (poorly, see my other email), which means we > can never change it. > >> QDataStream is black-box system for Qt to Qt exchange. > > The mere fact that such documentation exists contradicts this fact. > Plus, QDataStream's own documentation does not say anything like that > (at least, I can't find it. I'll be happily to be disproven)
Rational is quite simple, if i need a well documented exchange format, then i don't try to use a poorly documented one! I've always considered QDataStream a convenience persistent storage class for Qt application, not for exchange with "foreign" code. Same goes with QSettings, it hasn't been designed as an exchange file format, so i don't try to use it for that purpose. > >> If the other side of the pipe is arduino, maybe try to use JSON (very >> easy to use on Qt side), and i'm sure arduino as some library for >> this. > > ... and add a gigantic overhead for JSON's (de)serialization. Seems like > a terrible idea. You still want some sort of binary format. "Gigantic"? That's sounds very much speculative... They run HTTP servers over TCP/IP on arduino (just a random example). Yes JSON will add some overhead, as Thiago pointed out, CBOR [1] can be an alternative. And since we seem to be into premature optimisation, then let's roll your own, go for ASN.1 with PER [2], very compact indeed, but you'll have to deal with code complexity, both on Arduino and in Qt... JSON could still be a valid alternative, if Arduino has a ready-and-easy to use library, and the data exchange is not crazy (how many records/bytes per seconds are we talking?). What's more important here? dev time, CPU overhead, wire overhead, standard format? ... Chris [1] http://cbor.io/ [2] https://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One > > Cheers, > -- > Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer > KDAB (UK) Ltd., a KDAB Group company | Tel: UK +44-1625-809908 > KDAB - Qt, C++ and OpenGL Experts > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
