void main()
{
    import std.experimental.allocator;
    import std.stdio : write, writeln, writef, writefln;

    class Foo
    {
        public int id = 42;
        public double f = 4.2;
        public this()
        {
        }

        public this(int id)
        {
            this.id = id;
        }
    }

    Foo foo = theAllocator.make!Foo();

    writeln(foo.id);

    foo = theAllocator.make!Foo(5);

    writeln(foo.id);
}