John Bandhauer wrote:
> In general wrappedJS wrappers are going to give you a different pointer
> for every interface you QI it for - even if those interfaces
> share an inheritance relationship. The exception is nsISupports
> which *sometimes* shares a wrapper with another interface. Any
> xpcom object might also do this - so your code should be ready for
> this - but wrapped JS objects do it more.
Just FYI, Python is very similar to js in this regard.
> You should *never* be expecting equality of pointers that have not
> been QI'd to the same interface.
I thought the rules specifically state nsISupports? (I can't find a
reference!) I don't believe there are guarantees the same pointer will
be returned for any other interface than nsISupports? Whenever I
compare pointers I am very careful to QI for nsISupports on both - even
when they are the same IID. Is this unnecessary?
Actually, I should re-phrase the question - I am almost certain it is
currently unnecessary for all implemented components. But is it legal?
Thanks,
Mark.
