如何正确使用INetSharingManager？

Question

I'm a newbie C++ programmer, and using C++ Builder XE3, and I have a good Delphi background, and I'm trying to use INetSharingManager, but it gives me an error message:

E2352 Cannot create instance of abstract class 'INetSharingManager'

this is the code that I use:

INetSharingManager* NSManager = new INetSharingManager();

My questions are :

• How to properly use INetSharingManager in C++?
• and how to use INetSharingManager in Delphi, (if it's possible) ?

and thanks in advance.

Answer 1

This is an interface, and you cannot instantiate it like that. Remember that interfaces do not have implementation, so there's clearly no chance at all to instantiate them. You have to instantiate something else that implements the interface.

The C++ sample code here shows how to create one of these guys. Here's the key excerpt:

CoInitialize (NULL);

// init security to enum RAS connections
CoInitializeSecurity (NULL, -1, NULL, NULL, 
                      RPC_C_AUTHN_LEVEL_PKT, 
                      RPC_C_IMP_LEVEL_IMPERSONATE,
                      NULL, EOAC_NONE, NULL);

INetSharingManager * pNSM = NULL;    
HRESULT hr = ::CoCreateInstance (__uuidof(NetSharingManager),
                                 NULL,
                                 CLSCTX_ALL,
                                 __uuidof(INetSharingManager),
                                 (void**)&pNSM);

This code comes from the official Microsoft documentation for this library. You should read that documentation thoroughly.

You ask how to use this interface from Delphi. Well, you do exactly the same as you do in C++. Call CoCreateInstance to obtain an interface reference. Now that you can see how to do it from C++, it's simple enough to translate it to Delphi.

Answer 2

As the answer is fairly outdated I recommend following code:

HRESULT hr = E_FAIL; 
CoInitialize(nullptr);
INetSharingManager* pNetSharingManager = nullptr;
hr = CoCreateInstance(CLSID_NetSharingManager, 
nullptr,
CLSCTX_ALL, 
IID_INetSharingManager,
reinterpret_cast<LPVOID*>(&pNetSharingManager));

Tested and working code sample.