import std.stdio;
import std.string : format;

enum Op
{
    Equals,
    NotEquals,
}

struct BinaryExpr(T)
{
    T left;
    T right;
    Op op;
}

struct Column(T)
{
    T value;
    alias value this;

    bool opEquals(T b)
    {
        return b == value;
    }

    BinaryExpr!T opEquals(T b)
    {
        return BinaryExpr!T(this, b, Op.Equals);
    }
}

void filter(T)(BinaryExpr!T e)
{
    writeln(e);
}

class User
{
    Column!int id;
    Column!string name;
    Column!string password;

    public override string toString()
    {
        return "%d, %s, %s".format(id, name, password);
    }
}

void main()
{
    auto user = new User();
    with (user)
    {
        id = 10;
        name = "John Doe";
        password = "qwe123";
    }

    filter(user.id == 10);

    // Here is the error
    if (user.id == 10) {
        writeln("User ID is 10");
    }

    writeln(user);
}