COM - How to create a method that returns a pointer to an interface?

Question

How to create a method in COM that returns a pointer to an interface, this needs to be done inside the IDL file.

EDIT:

How do I implement this within a class:

STDMETHODIMP CBlah::get_Something(IOtherBlah** retval){
return m_protectedvar->QueryInterface(retval);
}
STDMETHODIMP CBlah::put_Somthing(IOtherBlah* rhs){
m_protectedvar = rhs;
return S_OK;
}

The above is not working. I'm getting the following error:

cannot instantiate abstract class with[ Base=Blah ] due to following members:
'HRESULT IBlah::putref_Something(IOtherBlah*)' : is abstract

sharptooth · Accepted Answer · 2010-01-26 13:20:58Z

5

Something like this:

 interface IYourInterface {
     HRESULT GetPointer( [out, retval]IInterface** );
 };

The caller will call it like this:

 IInterface* pointer = 0;
 HRESULT hr = yourInterfacePointer->GetPointer( &pointer );

answered Jan 26, 2010 at 13:20

sharptooth

171k110 gold badges545 silver badges1k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Phill Pafford Over a year ago

trying to do a get/set methods, one to set the object and one to get the pointer to the object/interface

sharptooth Over a year ago

No problem, use the snippet by user nobugz in the other answer.

Hans Passant · Accepted Answer · 2010-01-26 13:54:06Z

2

[ attributes here...]
interface IBlah : IDispatch {
  [id(1), propget]    HRESULT Something([out,retval] IOtherBlah** retval);
  [id(1), propputref] HRESULT Something([in] IOtherBlah* rhs);
};

answered Jan 26, 2010 at 13:54

Hans Passant

947k151 gold badges1.8k silver badges2.6k bronze badges

2 Comments

Hans Passant Over a year ago

@Phill - why did you unmark the answer? What else do you need?

Hans Passant Over a year ago

You have to write putref_Something(), not put_Somthing().

Collectives™ on Stack Overflow

COM - How to create a method that returns a pointer to an interface?

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related