[Interest] QCborValue and Qt types

Andrew Ialacci andrew at dkai.dk
Sun Dec 2 19:12:56 CET 2018

Hope it’s ok that I barge in :P

Are there any recommended strategies for serializing custom model objects?

For example a Person class with name, age, and gender properties. 

Or would I just write a 

QByteArray toCBOR() const 

method on all my model classes and create the CBOR object representation manually like with JSON. 

Sent from my iPhone

> On Dec 1, 2018, at 6:43 PM, Thiago Macieira <thiago.macieira at intel.com> wrote:
>> On Saturday, 1 December 2018 03:54:35 PST Konstantin Shegunov wrote:
>> Hello,
>> I'm evaluating Qt's (5.12) cbor implementation for a network transmission
>> protocol. I saw that few Qt types were tagged already (I imagine as a proof
>> of concept/preview). Are there plans to extend these to include more types
>> (e.g. QImage) or should I just stick to writing them as binary buffers?
>> As a follow-up what is the suggested way to pass *custom* types to QCbor*,
>> are they to be streamed through QVariant?
> Yes and no. See the attached draft spec (tag numbers are outdated) for a few 
> types I had been thinking of and already have an implementation for. Which 
> also reminds me I needed to send them to the CBOR IETF group for review.
> I was thinking of sticking at first to QtCore types, so QImage will not be 
> included. I'm not even sure how we could add support for types in other 
> libraries; possibly you'll need to register a serialisation and 
> deserialisation function like qRegisterStreamOperators does.
> And also note that we'll never get actual matching to Qt types. Like in the 
> attached geometry proposal, there's one type for size, not one for size and 
> one for size-float. This is important if you look at classes that are 
> identical but of different generations, like QVector4D and QQuaternion, or 
> worse functionally identical ones like QPixmap, QBitmap and QImage. We won't 
> get a standard tag that distinguishes them, since that distinction is not 
> useful outside of Qt. I'm open to ideas on how we can address that.
> -- 
> Thiago Macieira - thiago.macieira (AT) intel.com
>  Software Architect - Intel Open Source Technology Center
> <cbor-tags-geometry.rst>
> <cbor-tag-bitarray.rst>
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