SVG.Polyline = SVG.invent({
  // Initialize node
  create: 'polyline'

  // Inherit from
, inherit: SVG.Shape

  // Add parent method
, construct: {
    // Create a wrapped polyline element
    polyline: function(p) {
      // make sure plot is called as a setter
      return this.put(new SVG.Polyline).plot(p || new SVG.PointArray)
    }
  }
})

SVG.Polygon = SVG.invent({
  // Initialize node
  create: 'polygon'

  // Inherit from
, inherit: SVG.Shape

  // Add parent method
, construct: {
    // Create a wrapped polygon element
    polygon: function(p) {
      // make sure plot is called as a setter
      return this.put(new SVG.Polygon).plot(p || new SVG.PointArray)
    }
  }
})

// Add polygon-specific functions
SVG.extend(SVG.Polyline, SVG.Polygon, {
  // Get array
  array: function() {
    return this._array || (this._array = new SVG.PointArray(this.attr('points')))
  }
  // Plot new path
, plot: function(p) {
    return (p == null) ?
      this.array() :
      this.clear().attr('points', typeof p == 'string' ? p : (this._array = new SVG.PointArray(p)))
  }
  // Clear array cache
, clear: function() {
    delete this._array
    return this
  }
  // Move by left top corner
, move: function(x, y) {
    return this.attr('points', this.array().move(x, y))
  }
  // Set element size to given width and height
, size: function(width, height) {
    var p = proportionalSize(this, width, height)

    return this.attr('points', this.array().size(p.width, p.height))
  }

})