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[WebIDL] add text to discourage `InterfaceOwnedBySomeoneElse implements InterfaceIJustWrote;` and suggest `ConcreteObjectThatImplementsThatInterface implements InterfaceIJustWrote;` instead.

From: timeless <timeless@gmail.com>
Date: Mon, 29 Aug 2011 13:08:24 -0400
Message-ID: <CAACrNNexPfRn2aPgMZYac=8afVhwja7GDKXbZKbqg-Eq=v8YMg@mail.gmail.com>
To: public-script-coord@w3.org
I recently saw a snippet of Web IDL code that goes like this:

X implements Y;
interface Y: Z
Z implements P;

The problem is this:
  ConcreteObject A;
  A implements IFoo;
  A implements IBar;
  A implements IBaz;
  ConcreteObject B;
  B implements IFoo;

If someone decides that they have a `B` and want to make B's IFoo
interface do more, they might say:
IFoo implements IMyFooMore;

expecting it to make B more powerful -- but at the same time, it
causes random effects on A.

Note that we had this experience while working on Mozilla.

The rule which we tried to enforce is this:

Only the owner of IFoo is allowed to extend IFoo until IFoo is frozen,
at which point, IFoo MAY but probably SHOULD NOT be extended by

Roughly that translates into:

  You, owner of ConcreteObject X are free to use 'X implements IWhatever;', but
  You are NOT free to use 'IStandardsBodyThing implements IWhatever;'.

And I'd like to see text to this effect added to the specification.
Received on Monday, 29 August 2011 17:08:59 UTC

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