count = 0;
function Klacc(){
}
Klacc.extend = function(Child, Parent)
    {
        if (typeof Parent === 'undefined')
            Parent = Klacc;
        var F = function() { };
        F.prototype = Parent.prototype;
        Child.prototype = new F();
        Child.prototype.constructor = Child;
        Child.super = Parent.prototype;
    };
Klacc.prototype.as = function(cl)
{
if ( (typeof this._as === "object") && this._as[cl] )
{
  return this._as[cl];
}
var curr = this;
while ( curr.constructor.name !== cl ) curr = curr.constructor.super;

if ( typeof this._as === "undefined" )
{
  this._as = {};
}
else if ( typeof this._as !== "object")
{
  throw { context:this, message:"object already has reserved property \"_as\" invalid type" }
}
this._as[cl] = curr;
return curr;
}
Klacc.prototype.parentOf = function(cl)
{
  var curr = this.as(cl);
  return curr.constructor.super;
}

function A() {  }
Klacc.extend(A)
A.prototype.init = function(){ /* A.prototype.init */
  if (++count < 100)
    console.log('A.prototype.init.apply', this);
  this.name = 'A';
}


function B(){  }
Klacc.extend(B,A)
B.prototype.init = function(){ /* B.prototype.init; this - instance of D */
  if (++count < 100)
    console.log('B.prototype.init.apply', this);
console.log('Parent Of B', this.parentOf('B'));
this.parentOf('B').init.apply(this,arguments);

  this.extra = 'im B';
}

function C() {  }
Klacc.extend(C,B)
C.prototype.init = function(){ /* C.prototype.init; this - instance of D */
  if (++count < 100)
    console.log('C.prototype.init.apply', this);

console.log('Parent Of C', this.parentOf('C'))
    this.parentOf('C').init.apply(this,arguments);

  this.extraC = 'mimimi';
}
c= new C

function D() {  }

Klacc.extend(D,C)

D.prototype.init = function(){ /* D.prototype.init */
  if (++count < 100)
    console.log('D.prototype.init.apply', this);
console.log('Parent Of D', this.parentOf('D'))
    this.parentOf('D').init.apply(this,arguments);

}

d = new D

d.init()