Re: handling QueryInterface
Jason S <firstname.lastname@example.org> wrote:
What are some ways of overriding the default ATL QueryInterface?
COM_INTERFACE_ENTRY_* macros. E.g. your interface map could look like
COM_INTERFACE_ENTRY(IUnknown) // first entry must be simple
then almost all the work of QueryInterface is delegated to
My understanding of QueryInterface is that a given object has to
provide consistent transitivity, e.g. if you can ever successfully
QueryInterface from any of interfaces in set S = (I1, I2, I3, etc.) to
another, you have to always be able to get from any one of them to any
of the others, & can't decide to return E_NOINTERFACE conditionally
based on something.
I am, however, thinking of implementing an object that offers a
different set S of interfaces depending on how the object was
initialized, which appears to be legal -- my source being "Essential
COM" chapter 4 particularly page 164.
Yes, it is legal.
With best wishes,
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necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
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