Any way to declare a nest class structure in typescript?

Question

I\'m interested in defining an existing framework (openlayers.d.ts) but cannot figure out how to express the fact that OpenLayers.Layer is both a class and a namespace for O

Answer 1

As of 2016, I guess this is easier:

class A {
    static B = class { }
}

var a = new A();
var b = new A.B();

Answer 2

Use TypeScript's class expressions for this:

var OpenLayers = class {
    static Layer = class {
        static Markers = class {}
    }
}

Answer 3

You can use namespace/class merging to get an equivalent effect to nested classes. This example is adapted from Chapter 1 of Pro TypeScript.

You perform merging with a class and a namespace, or with a function and a namespace.

In all cases, the namespace must appear after the class or function for the merge to work.

Adapted example:

class Outer {

}

namespace Outer {
    export class Mid {

    }

    export module Mid {
        export class Inner {

        }
    }
}

var a = new Outer();
var b = new Outer.Mid();
var x = new Outer.Mid.Inner();

Answer 4

Currently there is no support for nested classes.

http://typescript.codeplex.com/workitem/460

Answer 5

This is a bit late but others may find it useful. This is how I did it to fool TS to accomplish the task.

declare module OpenLayers {
  interface Layer { 
   ....
  }

  interface Markers {
    ....
  }

  var Layer: {
    new(name:string, options?:any):Layer;
    prototype:Layer;
    Markers: { 
      new(params?:any):Markers;
      prototype: Markers;
    }
  }
}

var markers = new OpenLayers.Layer.Markers();

Answer 6

This seems like it has been fixed in versions 0.9.1.1 and later. You just have to create a module with the same name as the class where you want to nest types, and put your nested types in it.

More concretely, this is how you do it:

declare module a
{
    class b
    {
    }

    module b
    {
        class c
        {
        }
    }
}

var myB = new a.b();
var myC = new a.b.c();

This works as well when nesting types in typescript code with the export keyword:

export module a
{
    export class b
    {
    }

    export module b
    {
        export enum c
        {
            C1 = 1,
            C2 = 2,
            C3 = 3,
        }
    }
}

As mentioned by the user @recursive in the comments below, the order of declaration is important. So the class definition must be located before the module with the nested types.