[Bug]: Multiple inheritance with custom shapes not working (as expected?) about joint HOT 7 CLOSED

It is the defaults :)

• wrong order of merge arguments
• super.default is a function in CBase

class CLink extends CBase {
  defaults() {
    return joint.util.merge(
      {},
      super.defaults(),
      {
        type: "CLink",
        attrs: {
          line: {
            stroke: "#ccc",
            strokeWidth: 2
          }
        }
      },
    );
  }
}

from joint.

Ooohh! 🤔

Ok, I have another questions. Why CBase is merging super.defaults, but CLink is merging super.defaults()? What is the difference between using super.defaults as a value and calling super.defaults() as a function?

from joint.

The shapes.standard.Link class is defined via the define method which using the extend method of Backbone. If you create a Backbone.Model this way (ES5 way), the defaults is a property, not a method. Therefore CBase needs to access it as a property.

The ES Class CBase defines the defaults as a method. Therefore CLink has to call it as a function.

I recommend reading this article which should explain this in detail. Also reading this Backbone issue might be helpful.

from joint.

Oohh, now I get it. Good thing to know :)
Thank you!!

from joint.

I have an extra question 🙏

Would it be possible to extend from 2 classes using this method? Lets say that I have CBaseLinkA which defines the stroke color (using the defaults()) and CBaseLinkB which defines the strokeWidth (also using the defaults()) and the markup attribute. Would it be possible to do something like

class MyLink extends merge(CBaseLinkA, CBaseLinkB) {
  defaults() {
    return joint.util.merge(
      {
        attrs: { line: { fill: "red" } }
      },
      super.defaults() // ???? 
    )
  }
}

from joint.

Perhaps you can check this discussion.

from joint.

Hmmm, I think I saw similar stuff in SO, but I'm not really sure how to handle the defaults(), since that is threated in a very special way. I'll play around and report back if I find a way of achieving this!

from joint.