Hey Dan,

here is the context:

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DygraphLayout.prototype._evaluateLineCharts = function() {
  [...]
 this.dygraph_.dataHandler_.onLineEvaluated(...);
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danvk r
accessing a private member of an object (let alone methods on that member) 
is generally a code smell. I realize the separation of concerns between 
dygraph-layout.js and dygraph.js isn't the cleanest, but we should try to 
avoid making it worse. Perhaps add an onLineEvaluated_ method to the 
dygraph object? 

davideberlein 
Adding an onLineEvaluated_ to dygraphs kind of seems wrong to me because 
dygraphs is the one actually calling the evaluate() method. What would you 
think about one of these two solutions:
1.) calling an alternate callback:
this.layout_.evaluate();
this.dataHandler_.onLayoutEvaluated(...)
-> For this solution I would have to adapt my callback to be more general.

2.) adding a callback function to the layout.evaluate method.
this.layout_.evaluate(this.dataHandler_.onLineEvaluated)
-> the layout could then call the given callback in a more abstract way.