IUnknown is the fundamental COM (Component Object Model) interface, which the specification mandates must be implemented by all COM objects. All other COM interfaces derive from IUnknown. The IUnknown interface exposes methods for object lifetime management and the ability to access object functionality by retrieving references to other interfaces. (NOTE: This tag is related to Windows programming. Don't use it to mean something is "unknown" to you!)
Questions tagged [iunknown]
63 questions
12
votes
3 answers
Delphi: How to implement QueryInterface of IUnknown?
In Delphi, IUnknown is declared as:
function QueryInterface(const IID: TGUID; out Obj): HResult; stdcall;
Note: The output parameter is untyped
In my TInterfacedObject descendant i need to handle QueryInterface, so i can return an object that…
Ian Boyd
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10
votes
2 answers
Assigning interface pointers in a Delphi 6 class declaration?
Despite years of Delphi programming I just ran into a class declaration style I had never seen for a class that supports IUnknown:
TBCUnknown = class(TBCBaseObject, IUnKnown)
private
FRefCount: integer;
FOwner : Pointer;
protected
function…
Robert Oschler
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9
votes
4 answers
Does IUnknown::QueryInterface() increment the reference count?
If I have an IUnknown *ptr, do I need to call Release() on every interface I obtain through ptr->QueryInterface(), in addition to calling ptr->Release() when I'm done with ptr?
I used to think that the answer is "Yes", but this quote from MSDN…
user541686
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9
votes
2 answers
How to implement custom iterable class in VBA
I want to add a feature to my classes so I can use them in for-each loops.
I wrote hashmaps, arraylists, queues, sets and so on that I want to iterate over.
Now I'm looking for a way to implement the IUnknown class to build custom iterators.
I…
JayC667
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6
votes
3 answers
Must the IUnknown interface be re-implemented by every new COM class?
Sorry if this question seems obvious for everyone, but I am very new to COM. From the tutorial I see here http://www.codeguru.com/cpp/com-tech/activex/tutorials/article.php/c5567, it seems like every COM class created in C++ must implement its own…
Carl
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6
votes
0 answers
Why when trying to assign to a variant, an array for some non-IDispatch-exposing object type, is the array pointer assigned instead?
Summary
After declaring an array for some object type where the type doesn't use an interface that derives from COM's IDispatch interface (& so isn't properly set-up to enable [OLE] Automation's late-binding technology), trying to assign the array…
Mark Fernandes
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6
votes
3 answers
Implementing IUnknown in C#
I've been looking for an example of how to implement IUnknown in C#, but haven't found any decent references or solutions to this.
Should it be as simple as...
public interface IUnknown
{
UInt32 AddRef();
UInt32 QueryInterface([In] IntPtr…
Matthew Layton
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5
votes
2 answers
warnings about mystery interfaces in C# projects
Every time I build my C# Solution, I get a handful of warnings about interfaces that I've never seen or written. I tried Googling for some of them, but get no hits. Could these possibly be buried in an assembly I'm referencing? If so, is there…
Sarah Vessels
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5
votes
2 answers
Add, Remove Folder from IShellLibrary
I am attempting to write two functions that add and remove a folder from a IShellLibrary. I started with this, but the function produces an exception in System._IntfClear:
First chance exception at $000007FEFE 168BC4. Exception class $C0000005…
Bill
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3
votes
1 answer
Access violation casting IDispatch in XE2
We're using some old code (ComLib.pas created by Binh Ly) so we can use the enumeration interface on an (OleVariant) object:
type
TDispNewEnum = dispinterface
['{97079E31-6957-11D2-9154-0000B4552A26}'] // dummy
property _NewEnum: IUnknown…
Mick
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3
votes
3 answers
Why are COM pointer arguments cast as void instead of IUnknown?
Apologies if this is a stupid question, but I wasn't clear on why COM pointer arguments are typically cast as (void**) instead of (IUnknown**). And then sometimes IUnknown pointers are in fact used, like with IObjectWithSite::SetSite. Can anyone…
user12381459
3
votes
2 answers
Hook IDispatch v-table in C++
I'm trying to modify the behavior of an IDispatch interface already present in the system.
To do this my plan was to hook into the objects v-table during runtime and modify the pointers so it points to a custom hook method instead.
If I can get this…
monoceres
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3
votes
1 answer
What to do with a COM server method returning an undocumented IUnknown
Some of the methods of a COM interface, which I have imported from a type library (part of a hardware SDK), return or receive a value of type IUnknown. As an example, the SDK documentation specifies the methods as follows:
bool…
Gerald Menzel
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3
votes
2 answers
Convert/cast SAFEARRAY of IUnknowns to an iterable array of interface pointers
I have the following interface in C# with a class with a same name (without I) implementing it.
[ComVisible(true)]
[Guid("B2B134CC-70A6-43CD-9E1E-B3A3D9992C3E")]
public interface IOrder
{
long GetQuantity();
long GetOrderType();
long…
Mirek
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3
votes
2 answers
C++ Pointer to member function of an UNKNOWN CLASS
DISCLAIMER I DO NOT USE BOOST OR OTHER LIBRARIES
Finally I've learned how PointerToMemberFunction works. This is my example code.
#include
using namespace std;
class Foo
{
public:
void foo ( )
{
…
Kolyunya
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