Question regarding a free interface in C #

Question

I have the following class:

public class Fluently
{
  public Fluently Is(string lhs)
  {
    return this;
  }
  public Fluently Does(string lhs)
  {
    return this;
  }
  public Fluently EqualTo(string rhs)
  {
    return this;
  }
  public Fluently LessThan(string rhs)
  {
    return this;
  }
  public Fluently GreaterThan(string rhs)
  {
    return this;
  }
}

In English grammar, you cannot “equal something” or “do something more than something,” so I don’t want Is.EqualTo and Do.GreaterThan to be possible. Is there any way to limit it?

var f = new Fluently();
f.Is("a").GreaterThan("b");
f.Is("a").EqualTo("b");        //grammatically incorrect in English
f.Does("a").GreaterThan("b");
f.Does("a").EqualTo("b");      //grammatically incorrect in English

Thanks!

Answer 1

To enforce this type of thing, you will need several types (to limit accessibility from which context) - or at least several interfaces:

public class Fluently : IFluentlyDoes, IFluentlyIs
{
    public IFluentlyIs Is(string lhs)
    {
        return this;
    }
    public IFluentlyDoes Does(string lhs)
    {
        return this;
    }
    Fluently IFluentlyDoes.EqualTo(string rhs)
    {
        return this;
    }
    Fluently IFluentlyIs.LessThan(string rhs)
    {
        return this;
    }
    Fluently IFluentlyIs.GreaterThan(string rhs)
    {
        return this;
    }
}
public interface IFluentlyIs
{
    Fluently LessThan(string rhs);
    Fluently GreaterThan(string rhs);
}
public interface IFluentlyDoes
{    // grammar not included - this is just for illustration!
    Fluently EqualTo(string rhs);
}

Answer 2

My solution would be

public class Fluently
{
    public FluentlyIs Is(string lhs)
    {
        return this;
    }
    public FluentlyDoes Does(string lhs)
    {
        return this;
    }
}

public class FluentlyIs
{
    FluentlyIs LessThan(string rhs)
    {
        return this;
    }
    FluentlyIs GreaterThan(string rhs)
    {
        return this;
    }
}

public class FluentlyDoes
{
    FluentlyDoes EqualTo(string rhs)
    {
        return this;
    }
}

It is very similar to Gravell's, but a little easier to understand, in my opinion.