Shadow-root and extend

[Xavier Cochard]

Hello,

I am using 2 components A and B, both having a Template and a Script tag. Both templates also use conditional template.

I am confused when extending B by A, that two "#shadow-root" appear while inspecting the dom.

<my-element-B ....>

  |> #shadow-root  (from B)

  |> #shadow-root  (from A)

</my-element-B>

Is there a way to only see B such as:

<my-element-B ....>

  |> #shadow-root  (from B)

</my-element-B>

In that sense I only want to extends the prototype and fully override the Template.

Thanks

Xavier

(using chrome 36 and latest polymer)

[Rob Dodson]

While the shadow-root from A is present, it shouldn't actually render anything. It's there in case you want to use the shadow element to create a shadow insertion point.

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[Xavier Cochard]

It doesn't render anything. But I was worried about performances mainly. Also for debugging purpose it would be a bit easier if not there, as not needed for my case.

Thanks for the link and explanation.

[Rob Dodson]

There is a cost associated with creating shadow-roots. Since it sounds like A and B share some behavior, but don't share content, it might make more sense to factor that behavior into its own base class/element that both A and B extend. Or add the behavior using something like Platform.mixin (which is unfortunately undocumented, but it basically lets you combine prototypes. here's an example)

[Xavier]

That's sound good. 

I re-factored to exclude the content from the base (A) and it feels slightly faster. At least it's cleaner.

Thanks;)