4 ms·

It just looks like C++ templates with a slightly different syntax ..

azakai 2y ago
Exactly, the point is that C++ added templates as a huge new language feature, while in Zig it is just one of the things that is immediately possible thanks to comptime.
throwawaymaths 2y ago
well, not quite since you can pass non-type things of generally any level of data type complexity (as long as it's comptime-valid, which only excludes certain types of mutation), and do stuff with them that you couldnt in c++. fn MyType(T: type, comptime tag: [] u8, comptime count: usize) type { const capitalized = some_module.capitalize(tag); return struct{ fn name() []const u8 { return capitalized; } array: [count]T, }; } for example
- Wumpnot 2y ago
  That example looks easy enough to replicate in C++ with consteval + template, basically the same except a few minor syntax changes.
  - Maxatar 2y ago
    You absolutely can't do that in C++ with consteval + template. C++ would need support for reflection to do that, and maybe it will get it in 10 years, maybe not, but as of today this would not be possible. Furthermore, the original argument wasn't about whether something can or can't be done in C++, it was that this one feature in Zig subsumes what would require a multitude of features from C++, such as consteval, templates, SFINAE, type traits, so on so forth... Instead of having all these disparate features all of which work in subtly different ways, you have one single feature that unifies all of this functionality together.
    - steveklabnik 2y ago
      You're not wrong in general here, but C++ is going to get the core of reflection in C++26. I'm not sure enough of the details to know if it supports doing this, however. Rust on the other hand... that might be ten years.
      - pcwalton 2y ago
        There are various reflection crates available on crates.io, as you know.
        steveklabnik 2y ago
        Yeah, I always wished that the reflect crate got further along than it has. I still think that language support us important, but unfortunately due to what happened, I suspect that will take a long time. And that’s disappointing.
        pcwalton 2y ago
        We Bevy users use Rust reflection on a daily basis, and are very happy with it :) I agree it'd be nice if it weren't confined to our community, though.
        steveklabnik 2y ago
        I should check it out, I haven't had an actual use-case for reflection lately, so I haven't given bevy_reflect a try yet, but when I do, I'll make sure to give it a shot.
        Ygg2 2y ago
        How does it do reflection on third party types (non-Rust, non-Bevy types)? Those that don't derive Reflect? Don't coherence rules prevent it?
        pcwalton 2y ago

Exactly, the point is that C++ added templates as a huge new language feature, while in Zig it is just one of the things that is immediately possible thanks to comptime.

throwawaymaths 2y ago

well, not quite since you can pass non-type things of generally any level of data type complexity (as long as it's comptime-valid, which only excludes certain types of mutation), and do stuff with them that you couldnt in c++. fn MyType(T: type, comptime tag: [] u8, comptime count: usize) type { const capitalized = some_module.capitalize(tag); return struct{ fn name() []const u8 { return capitalized; } array: [count]T, }; } for example

Wumpnot 2y ago
That example looks easy enough to replicate in C++ with consteval + template, basically the same except a few minor syntax changes.
- Maxatar 2y ago
  You absolutely can't do that in C++ with consteval + template. C++ would need support for reflection to do that, and maybe it will get it in 10 years, maybe not, but as of today this would not be possible. Furthermore, the original argument wasn't about whether something can or can't be done in C++, it was that this one feature in Zig subsumes what would require a multitude of features from C++, such as consteval, templates, SFINAE, type traits, so on so forth... Instead of having all these disparate features all of which work in subtly different ways, you have one single feature that unifies all of this functionality together.
  - steveklabnik 2y ago
    You're not wrong in general here, but C++ is going to get the core of reflection in C++26. I'm not sure enough of the details to know if it supports doing this, however. Rust on the other hand... that might be ten years.
    - pcwalton 2y ago
      There are various reflection crates available on crates.io, as you know.
      - steveklabnik 2y ago
        Yeah, I always wished that the reflect crate got further along than it has. I still think that language support us important, but unfortunately due to what happened, I suspect that will take a long time. And that’s disappointing.
        pcwalton 2y ago
        We Bevy users use Rust reflection on a daily basis, and are very happy with it :) I agree it'd be nice if it weren't confined to our community, though.
        steveklabnik 2y ago
        I should check it out, I haven't had an actual use-case for reflection lately, so I haven't given bevy_reflect a try yet, but when I do, I'll make sure to give it a shot.
        Ygg2 2y ago
        How does it do reflection on third party types (non-Rust, non-Bevy types)? Those that don't derive Reflect? Don't coherence rules prevent it?
        pcwalton 2y ago