Hi Vitali,
What you propose looks pretty similar to what I've had in mind for a while
for "inline structs".
I might do it more like:
struct Vector3f inlineable {
// `inlineable` keyword generates code that uses dynamic field offsets
// from a table at runtime, thereby enabling inlining with varying
layouts.
x @0 :Float32;
y @1 :Float32;
z @2 :Float32;
}
struct MyAwesomeStruct {
foo @[2..4] :Vector3f;
// typical use: layout is like a group, but the type is Vector3f
bar @[0..1,5] :Vector3f;
// split use; useful when the inlined struct adds new fields.
baz @[6] :Vector3f;
// incomplete use; produces compiler warning like:
// Vector3f has been extended with two new fields; to use them
you must assign two more numbers.
qux @[7..9] :List(Float32);
// inline list, always has 3 elements.
}
Unfortunately I don't have any timeline for implementing this feature, and
I do worry that it will be overcomplicated...
-Kenton
On Wed, Sep 11, 2019 at 2:47 PM <[email protected]> wrote:
> Is there any support for strong type aliasing? I see it on the roadmap but
> I'm guessing no progress has been done on that front?
>
> The specific use-case I'm dealing with is time & wanting to ensure the
> correct units and epoch can be used (e.g. define a function taking a
> monotonic_clock::timepoint and return a strongly typed 64-bit integer
> nanoseconds that's typed to represent network time so that when the other
> side reads it it needs to reverse convert.
>
> More advanced would be to be able to define a Vector3f data type that I
> know will only ever have 3 floats that I can reuse in a bunch of places
> without paying for the cost of it being a separate struct (.e.g it would
> take an "offset" field number & use up offset + N). So something like:
>
> group@N Vector3f {
> x @N[0] :float;
> y @N[1] :float;
> z @N[2] :float;
> }
>
> struct MyAwesomeStruct {
> ...
> vec3 @10 :Vector3f@10;
> vec3 @12 :Vector3f@12;
> }
>
> The actual syntax that would make sense I have no opinion on. This is
> intended to just communicate what I would like the behaviour to look like.
> It would ideally actually be typed in C++ too rather than purely a
> convenience schema syntax.
>
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