boxing a value in Zig

box.zig

const std = @import("std");
const Allocator = std.mem.Allocator;

pub fn box(allocator: Allocator, value: anytype) !*@TypeOf(value) {
    const ptr = try allocator.create(@TypeOf(value));
    ptr.* = value;
    return ptr;
}

test {
    const a = std.testing.allocator;
    const p = try box(a, @as(u32, 12345));
    defer a.destroy(p);
    try std.testing.expectEqual(12345, p.*);
    p.* = 67890;
    try std.testing.expectEqual(67890, p.*);
}