Uncommenting a line for a platform-specific feature isn't really any more difficult than decorating a function, adding a pre-processor gate, or any of the other normal ways of doing it.
you might [reasonably] say you can't care about that kind of simplicity, which is fine; but radical simplicity is definitely one of the major charms of zig.
(and you don't use the zig feature by commenting/uncommenting, it's via inspection of the environment/flags in the comptime code.)
You don't need a full preprocessor with macros and other evil stuff. Just #define and #ifdef would solve this without allowing wrong code that randomly disappears. And learning and understanding these two directives requires zero mental effort.
Yes. It's exactly that, because Zig very aggressively evaluates values that are known at compile time. It's as simple as:
if (builtin.os.tag == .linux) {
// Everything here only exists if compiling for Linux.
}
The same feature is also used for specializing generic containers to specific types (an idea that became famous after the resounding success of std::vector<bool>) so that for example arraylists of u8 expose a Writer but arraylists of f64 do not. Most code that is conditional on T == u8 won't typecheck if T != u8.
I guess more generally these features are used for implementing fmt, json encoders and decoders, etc. None of these thing would work if code conditional on the type had to typecheck for all types.
If it's a comptime constant by "mistake" then it would have resulted in the same wrong behaviour at runtime.
At the end of the day, this is pretty equivalent. Not sure if this is a net gain or not.
Conditional compilation is needed, moving the feature from the preprocessor stage to a lazy evaluator is probably costlier for the compiler and it might also be costlier for the IDE to highlight active/inactive parts of the code.
From the user point of view, this is very close, mostly a cosmetic change.
Moreover, I can grep for preprocessor defines, attributes, and such by name.
There's no way to grep a project for code commented out to prevent execution on some platforms.