This is probably gonna be super easy to answer but... consider:

const class Foo
{
  const Str? name

  new make(|This| f){f(this)}

  Foo setName(Str newName)
  {
    return ???(newName)
  }
}

const class Bar : Foo
{
  new make(|This| f):super(f){}
}

Now if I want to call Bar.setName(Str) I want it to return an object back of class Bar, not of class Foo. Need some help filling in the blanks.

You can use This return type:

const class Foo
{
  const Str? name

  new make(|This| f){f(this)}

  virtual This setName(Str newName)
  {
    Foo { it.name = newName }
  }
}

const class Bar : Foo
{
  new make(|This| f):super(f){}

  override This setName(Str newName)
  {
    Bar { it.name = newName }
  }
}

So there's no way of doing this without having a virtual method and overriding it for every subclass? Hmm I might resort to a different approach.

The only other way would be to use reflection.

Is your problem a static typing issue, or just how to create instances of the proper class?

If it is creating instances, then just use typeof.make. Since your constructor takes an it-block, it depends on what you want there. But you can use reflection to build an it-block too using Field.makeSetFunc.

@Brian I think thats exactly what I was looking for. So it would be something like this?

const class Foo
{
  const Str? name

  new make(|This| f){f(this)}

  Foo setName(Str newName)
  {
    f := Field.makeSetFunc(Foo#name:newName)
    return this.typeof.make([f])
  }
}

const class Bar : Foo
{
  new make(|This| f):super(f){}
}

Basic idea, the makeSetFunc takes a function:

Field.makeSetFunc( [#name: "someName"])