890579 - sdk/system/events subject wrapping defeats many use cases

Status: RESOLVED INCOMPLETE

(Add-on SDK Graveyard :: General, defect, P3)

Description

[Erik Vold [:erikvold] (please needinfo? me)]

I some use cases when one is using the observer service to post/emit a notification, the subject provided is altered.  Using sdk/system/events the subject is wrapped and thus unobtainable to the add-on making & emitting the notification..

With the old sdk/deprecated/observer-service this use case was supported..

For instance this is how Adblock Plus allows some extensions to extend it.

Comment 1

[Erik Vold [:erikvold] (please needinfo? me)]

* For instance this is how Adblock Plus allows some extensions to extend it this way.

Comment 2

[Erik Vold [:erikvold] (please needinfo? me)]

(In reply to Erik Vold [:erikvold] [:ztatic] from comment #2)
> With the old sdk/deprecated/observer-service this use case was supported..

Hmm I don't know why I said this.. it looks like the wrapping has been around since 0.8 at least..  not sure it's a good idea still.

Comment 3

[Dave Townsend [:mossop]]

(In reply to Erik Vold [:erikvold] [:ztatic] from comment #0)
> I some use cases when one is using the observer service to post/emit a
> notification, the subject provided is altered.  Using sdk/system/events the
> subject is wrapped and thus unobtainable to the add-on making & emitting the
> notification..

That doesn't match my reading of the code but maybe I'm missing something. Looks like when emitting a notification we wrap the subject in an xpcomy object but then unwrap it when receiving notifications.

Comment 4

[Erik Vold [:erikvold] (please needinfo? me)]

(In reply to Dave Townsend (:Mossop) from comment #3)
> (In reply to Erik Vold [:erikvold] [:ztatic] from comment #0)
> > I some use cases when one is using the observer service to post/emit a
> > notification, the subject provided is altered.  Using sdk/system/events the
> > subject is wrapped and thus unobtainable to the add-on making & emitting the
> > notification..
> 
> That doesn't match my reading of the code but maybe I'm missing something.
> Looks like when emitting a notification we wrap the subject in an xpcomy
> object but then unwrap it when receiving notifications.

Yeah that is all right, you missed my point.

Comment 5

[Erik Vold [:erikvold] (please needinfo? me)]

If anyone should handle this it is Irakli.  I've been against the whole design of system/events in the first place.

Comment 6

[Jordan Santell [:jsantell] [@jsantell]]

Pinging Irakli for approval of unwrapped subjects -- I don't think it'd be too dangerous (also being a lower level API) to expose the unwrapped counterparts.

Comment 7

[Jordan Santell [:jsantell] [@jsantell]]

Looks like Alex requested the same thing previously bug 834288

Comment 9

[Irakli Gozalishvili [:irakli] [:gozala] [@gozala]]

What is the request here exactly ? Not to wrap subjects ? If so note if `wrappedJSObject` property isn't present observer will receive empty object which will be useless.

If you have something along this lines in mind instead:
https://github.com/mozilla/addon-sdk/blob/master/lib/sdk/output/system.js#L57-L64
https://github.com/mozilla/addon-sdk/blob/master/lib/sdk/input/system.js#L88-L96 

Than sure that's fine by me.

Comment 10

[Firefox Bug Husbandry Bot]

https://bugzilla.mozilla.org/show_bug.cgi?id=1399562