Some fun with the Zig programming language

zig1.zig

const std = @import("std");

const Controller = struct {
    up: u1,
    down: u1,
    left: u1,
    right: u1,
};

pub fn main() void {
    structInfo(Controller);
    structInfo(struct {});
    listStructFields(Controller);
    listStructFields(struct {
        some_i32: i32,
        my_controller: Controller,
        ptr_to_controller: *Controller,
    });
    listStructFields(union { foo: i32 });
    listStructFields(enum { Hello });
    listStructFields(struct {});
}

fn structInfo(comptime T: type) void {
    std.debug.warn("Size of {}: {}\n", @typeName(T), @intCast(u64, @sizeOf(T)));
}

fn listStructFields(comptime T: type) void {
    const TypeId = @import("builtin").TypeId;
    const strct = switch (@typeInfo(T)) {
        TypeId.Struct => |s| s,
        else => return,
    };

    std.debug.warn("Listing fields for {}:\n", @typeName(T));

    if (strct.fields.len > 0) {
        inline for (strct.fields) |field| {
            std.debug.warn("  {}: {}\n", field.name, @typeName(field.field_type));
        }
    } else {
        std.debug.warn("  no fields for struct.\n");
    }
}