Transferables

[whatwg]

Transferables

[marcoscaceres]

The use case for this is really having a dictionary that is passed to .postMessage().

Today, we use any data:

interface WhatEver{
   void postMessage(DOMString url, any data, NfcMessageDeliveredCallback); 
}

But what I want is something like:

transferable dictionary WhateverData {

}

interface WhatEver{
   void postMessage(DOMString url, WhateverData data, someCallBack); 
}

When WhateverData.postMessage() is invoked, the structured clone algo would be run on WhateverData.

cc: @kenchris

[bzbarsky]

Is the idea to only clone some of the dictionary's properties but not all of them?

Or is the idea to not change UA behavior at all from what it would be with "any" and invoking the structured clone algorithm in prose, so this would just be a form of documentation?

[marcoscaceres]

Is the idea to only clone some of the dictionary's properties but not all of them?

Yes, this is what I was thinking.

Or is the idea to not change UA behavior at all from what it would be with "any" and invoking the structured clone algorithm in prose, so this would just be a form of documentation?

That's what I'm kinda hoping we can discuss in this bug. If you are passing a transferable Dictionary, then I think it would be fine to just throw out all the unknown stuff in the cloning process.

[bzbarsky]

Yes, this is what I was thinking.

OK. Note that you can already do this by having the dictionary in the IDL and then in prose converting the dictionary to a JS value and then structured cloning that value. It's a bit nonobvious, but quite possible.

Is this something people commonly want to do?

[marcoscaceres]

OK. Note that you can already do this by having the dictionary in the IDL and then in prose converting the dictionary to a JS value and then structured cloning that value. It's a bit nonobvious, but quite possible.

Agree - it's certainly doable. Just figured it would be cleaner to take it out of prose.

Is this something people commonly want to do?

I don't think it's very common - but I've seen it come up a few times in various context/discussions. I'll see if I can gather more real examples over time.

[marcoscaceres]

(closing for now ... thanks for clarifications @bzbarsky!)