CODEWITHSUNDEEP
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user565660
user565660

Reputation: 1191

Having problems getting idl declaration with pointer to vector for a getter

I am trying to specify a vector in an IDL specification of property getter. I am new to C++ so bear with me. The object IThis is a hypothetical object of anything. I am getting a compile error at the id declaration expecting a type specifier. Thank you very much!!!!!!!!!!!!!!!

STDMETHOD(get_ThisList)(vector<IThis*> *value) 
{
   *value = mThisList;
   return S_OK;   
}

vector<IThis*> mThisList;

[propget] IDLAPI ThisList([out,retval] vector<IThis*>* value);

Upvotes: 2

Views: 1001

Answers (2)

Igor Tandetnik
Igor Tandetnik

Reputation: 52561

You can't use vector in a COM interface, with IDL or otherwise. You could return a safearray of interface pointers; it would look like this:

// In IDL
[propget]
HRESULT ThisList([out,retval] SAFEARRAY(IThis*)* value);

// In C++
HRESULT get_ThisList(SAFEARRAY** value);

Other alternatives include a conformant array (though this is inadvisable for an automation interface, as yours appears to be), and a separate collection object that represents a list of objects.

An implementation for get_ThisList might look something like this:

STDMETHODIMP MyObject::get_ThisList(SAFEARRAY** value) {
  if (!value) return E_POINTER;

  SAFEARRAYBOUND bound = {mThisList.size(), 0};
  *value = SafeArrayCreate(VT_UNKNOWN, 1, &bound);

  IUnknown** data;
  SafeArrayAccessData(*value, (void**)&data);
  for (int i = 0; i < mThisList.size(); ++i) {
    (data[i] = mThisList[i])->AddRef();
  }
  SafeArrayUnaccessData(*value);
  return S_OK;
}

Error handling is left as an exercise for the reader.

Upvotes: 3

utnapistim
utnapistim

Reputation: 27365

std::vector is a C++ class; IDL (interface definition language - different language) has no concept of it.

"expecting a type specifier" means the IDL compiler doesn't recognize std::vector as a type.

You will have to return a pointer to array of IThis as the return value, and put it into a smarter object at the caller's site.

Upvotes: 0

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