在C ++ Builder中使用COM

Question

I'm new to COM libraries and I'm stuck on using a COM DLL in my C++ Builder (XE2) application. DLL is registered. Which are the steps that allows me to create objects belonging to such DLL and invoke their methods? I mean statically.

I couldn't find a tutorial, while I saw different ways:

1. Component > Import component > it produces a new wrapper unit... and then what?

2. import the DLL with an absolut path (why? it is registered in the system)

    #import "C:\\Path\\to\\the\\LIB1.dll" rename_namespace ("LIB1") 

   ... and then what?

3. use CoCreateInstance ... how exactly? without import/include?

In Visual C# I deal with it simply adding a reference and a using !

I'm very confused! Any help is appreciated.

Answer 1

I found a way (but tell me if there are better ones):

• Component > Import component... > Import a Type Library > select the library
• Unit Dir Name = and uncheck "Generate Component Wrappers"
• "Add unit to MyProject.cbproj project" > Finish
• in the client class > File > Use Unit... > select the unit that was created

• in the client class write this code for using the COM DLL:

   CoInitialize(NULL); //Init COM library DLLs ICompany *company; HRESULT hr = CoCreateInstance ( CLSID_Company, NULL, CLSCTX_INPROC_SERVER, IID_ICompany, (void**) &company ); if (SUCCEEDED (hr)) { //TODO here you can use your company object! //and finally release such resource company->Release(); } CoUninitialize(); 

Where Company was the original class, exposed by the DLL, which I wanted to intantiate.

Introduction to COM - What It Is and How to Use It. helped me a lot.

Note that this requires the creation of *_TLB.* and *_OCX.* units . Is there a way that avoids it?