dart 计算两点间距离

import 'dart:math' ;
class Point{
  Point(this.x,this.y);
  distanceTo(other){
    var dx= x-other.x;
    var dy= y-other.y;
    return sqrt(dx*dx+dy*dy);
  }
  var x,y;
}

main(){
  var p= new Point(2,3);
  var q= new Point(3,4);
  print('distance from p to q =${p.distanceTo(q)}');
}