Handling of members of aggregate types

[zakalawe]

When T is an aggregate type, eg struct Rect { int x; int y; int width; int height; }

It would be great to be able to access members of Property, i.e that:

Property<Rect> r;
auto widthProp = makeBoundProperty(r.width);

This slightly overlaps with what @lemirep is asking about in #28, except in my case the aggregate does not contain Property<> members. The desired behaviour can be done using a function argument to makeBoundProperty : the question is whether some overload of operator-dot (and ->, presumably) could synthesise the access.

[zakalawe]

There's an interesting case here that widthProp could in simple cases be write-able. However, this would need a different API, to track const- vs non-const bindings, I guess.

So you could do:

Property<Rect> r;
auto widthProp = makeBoundPropery(r.width);
widthProp = 99;

and this would trigger bindings on r

I can guess making this work for arbitrary deep nesting is impossible, but for the common case of types such as color, date or vec3 / mat4, it feels like it would be useful enough to support.

[LeonMatthesKDAB]

There's an interesting case here that widthProp could in simple cases be write-able. However, this would need a different API, to track const- vs non-const bindings, I guess.

I'd say this is a separate issue, that also came up frequently, which is two-way bindings. (i.e. assign the "result" of a binding and if it's direct, write it into the source).

Otherwise adding support for . and -> operators is definitely interesting, but will need more research.