Inspired by zimpl library, I implemented a zig version（GitHub - passchaos/zigraft: trait power, grafted onto Zig · GitHub ） similar to rust’s trait, extending support for：
- trait associated types
- trait method default implementation
- trait inheritance
- trait projection.
The usage of this library is relatively simple. You can refer to tests.zig for the usage methods. For example, the following trait combination inheritance:
pub fn Seekable(comptime T: type) type {
return struct {
const SeekError: type = zigraft.associatedType(T, "SeekError", zigraft.associatedType(T, "ReadError", anyerror));
seekTo: fn (T, u64) SeekError!void,
};
}
pub fn ReadSeek(comptime T: type) type {
return zigraft.Compose(T, .{ Reader, Seekable }, struct {});
}
pub fn BufRead(comptime T: type) type {
return zigraft.Compose(T, .{Reader}, struct {
fillBuf: fn (T) anyerror![]const u8,
consume: fn (T, usize) void,
});
}
pub fn Stream(comptime T: type) type {
return zigraft.Compose(T, .{ Named, ReadSeek, BufRead }, struct {
describeAndRead: fn (T, []u8) anyerror!usize = struct {
fn call(self: T, out: []u8) anyerror!usize {
const impl = zigraft.Impl(Stream, T){};
// std.debug.print("stream={s}\n", .{self.name});
return impl.read(self, out);
}
}.call,
});
}