Hello everyone, I've been interested in a zig plugin for a few weeks now,
too : I gave it a try and the prototype is available here [1].
It is clearly missing a lot of features, but the general structure is there
and I think that by now it is interesting (at least for the purpose of
discussion !).
One can find :
- The plugin, of course, implemented in (ugly but easily modifiable) C++ in
`src/plugin/`, that generates zig files from generation requests.
- A capnp zig module in `src/` and `src/capnp/ that contains the runtime
code. Again, it is partial, but a lot of things are there already :
- Writing of structures, groups, enums, primitive types and lists
- Reading of structures, primitive types and lists.
- Compressor and Decompressor, implemented as Zig's reader and writer
(there are tests for those, in tests.zig).
- Use-cases, in `examples/`, which I find interesting as they demonstrate
how a user can use a StreamSource (for reading) and an Allocator (for
writing).
- I think the best place to start exploring the code, if need be, is
`examples/emitter.zig`. It writes a file that respects the primitive.capnp
schema. (The unionmess.capnp one is still WIP).
Again, I don't know if any other implementation exist, but I'll continue to
work on this version (not much in the next few months, though).
Still I'm totally interested in the discussion that might follow :)
For instance :
- How can one manage groups correctly ?
- Is the reader/writer approach for decompression a good idea or a bad idea
? I like the fact that it is quite composable with other kind of
readers/writers.
- What do you think of the View/Stencil notation instead of Reader/Builder
? (which I find clearly nicer personally, but the downside of changing
names is an obvious limitation).
About the remarks on a direct mapping to zig structs : I didn't try this
approach ; my prototype is much more conventional in this regard, and you
will simply find getters and setters (without keys as enums).
Hugo
[1] https://gitlab.com/Zarzwick/capnproto-zig-alternative
PS : Hopefully I'm not necrobumping anything by replying here (otherwise
I'm sorry). I saw this thread before going into my own implementation but
still wanted to try things out before diving in the discussion.
PS : The ROADMAP.txt is not exactly up-to-date.
Le lundi 15 novembre 2021 à 01:09:01 UTC+1, i...@zenhack.net a écrit :
> Quoting Daurnimator (2021-11-14 19:00:47)
>
> > Some misc notes:
> >
> > - I recall issues with using zig structs, as there is no way to e.g.
> > little-endian integer type
> > - Zig doesn't have anonymous fields
> > - Things would be nicer with https://github.com/ziglang/zig/issues/6478
>
> Yeah, I would not try to map capnproto structs directly to
> language-native structs, except as part of an up-front parsing API for
> performance-insensitive use. The normal thing is to just define wrapper
> types with accessors. Note that even with control over layout, a
> struct's data section can be shorter or longer than what the compiled
> schema suggests, so you still end up needing to do a bounds check.
>
> -Ian
>
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