ptr::CreateInstance

Статья
10/16/2008

Creates an instance of a COM object within a com::ptr.

void CreateInstance(
   System::String ^ progid,
   LPUNKNOWN pouter,
   DWORD cls_context
);
void CreateInstance(
   System::String ^ progid,
   LPUNKNOWN pouter
);
void CreateInstance(
   System::String ^ progid
);
void CreateInstance(
   const wchar_t * progid,
   LPUNKNOWN pouter,
   DWORD cls_context
);
void CreateInstance(
   const wchar_t * progid,
   LPUNKNOWN pouter
);
void CreateInstance(
   const wchar_t * progid
);
void CreateInstance(
   REFCLSID rclsid,
   LPUNKNOWN pouter,
   DWORD cls_context
);
void CreateInstance(
   REFCLSID rclsid,
   LPUNKNOWN pouter
);
void CreateInstance(
   REFCLSID rclsid
);

Параметры

progid
A ProgID string.
pouter
Pointer to the aggregate object's IUnknown interface (the controlling IUnknown). If pouter is not specified, NULL is used.
cls_context
Context in which the code that manages the newly created object will run. The values are taken from the CLSCTX enumeration. If cls_context is not specified, the value CLSCTX_ALL is used.
rclsid
CLSID associated with the data and code that will be used to create the object.

Исключения

If the com::ptr already owns a reference to a COM object, CreateInstance throws InvalidOperationException.

This function calls CoCreateInstance and uses ThrowExceptionForHR to convert any error HRESULT to an appropriate exception.

Заметки

CreateInstance uses CoCreateInstance to create a new instance of the specified object, identified either from a ProgID or a CLSID. The com::ptr references the newly created object and will automatically release all owned references upon destruction.

Пример

This example implements a CLR class that uses a com::ptr to wrap its private member IXMLDOMDocument object. The class constructors use two different forms of CreateInstance to create the document object either from a ProgID or from a CLSID plus a CLSCTX.

// comptr_createinstance.cpp
// compile with: /clr /link msxml2.lib
#include <msxml2.h>
#include <msclr\com\ptr.h>

#import <msxml3.dll> raw_interfaces_only

using namespace System;
using namespace System::Runtime::InteropServices;
using namespace msclr;

// a ref class that uses a com::ptr to contain an 
// IXMLDOMDocument object
ref class XmlDocument {
public:
   // construct the internal com::ptr with a null interface
   // and use CreateInstance to fill it
   XmlDocument(String^ progid) {
      m_ptrDoc.CreateInstance(progid);   
   }
   XmlDocument(REFCLSID clsid, DWORD clsctx) {
      m_ptrDoc.CreateInstance(clsid, NULL, clsctx);
   }

   // note that the destructor will call the com::ptr destructor
   // and automatically release the reference to the COM object

private:
   com::ptr<IXMLDOMDocument> m_ptrDoc;
};

// use the ref class to handle an XML DOM Document object
int main() {
   try {
      // create the class from a progid string
      XmlDocument doc1("Msxml2.DOMDocument.3.0");

      // or from a clsid with specific CLSCTX
      XmlDocument doc2(CLSID_DOMDocument30, CLSCTX_INPROC_SERVER);
   }
   catch (Exception^ e) {
      Console::WriteLine(e);   
   }
}

Требования

Header file <msclr\com\ptr.h>

Namespace msclr::com

См. также

Основные понятия

ptr Members

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