WRL integration (C++/CX)
You freely can mix WRL code with Windows Runtime C++ Template Library (WRL) code. In the same translation unit, you can use objects declared with WRL handle-to-object (^) notation and WRL smart pointer (ComPtr<T>) notation. However, you must manually handle return values, and WRL HRESULT error codes and WRL exceptions.
WRL development
For more information about authoring and consuming WRL components, see Windows Runtime C++ Template Library (WRL).
Example
The following code snippet demonstrates using WRL and WRL to consume Windows Runtime classes and examine a metadata file.
The example is taken from a code snippet in the Building Microsoft Store apps forum. The author of this code snippet offers the following disclaimers and stipulations:
C++ doesn't provide specific APIs to reflect on Windows Runtime types, but Windows metadata files (.winmd) for a type are fully compatible with CLR metadata files. Windows provides the new metadata discovery APIs (RoGetMetaDataFile) to get to the .winmd file for a given type. However, these APIs are of limited use to C++ developers because you can't instantiate a class.
After the code is compiled, you'll also need to pass Runtimeobject.lib and Rometadata.lib to the Linker.
This snippet is presented as-is. While it is expected to work correctly, it possibly can contain errors.
#include <hstring.h>
#include <cor.h>
#include <rometadata.h>
#include <rometadataresolution.h>
#include <collection.h>
namespace ABI_Isolation_Workaround {
#include <inspectable.h>
#include <WeakReference.h>
}
using namespace ABI_Isolation_Workaround;
#include <wrl/client.h>
using namespace Microsoft::WRL;
using namespace Windows::Foundation::Collections;
IVector<String^>^ GetTypeMethods(Object^);
MainPage::MainPage()
{
InitializeComponent();
Windows::Foundation::Uri^ uri = ref new Windows::Foundation::Uri("http://buildwindows.com/");
auto methods = GetTypeMethods(uri);
std::wstring strMethods;
std::for_each(begin(methods), end(methods), [&strMethods](String^ methodName) {
strMethods += methodName->Data();
strMethods += L"\n";
});
wprintf_s(L"%s\n", strMethods.c_str());
}
IVector<String^>^ GetTypeMethods(Object^ instance)
{
HRESULT hr;
HSTRING hStringClassName;
hr = instance->__cli_GetRuntimeClassName(reinterpret_cast<__cli_HSTRING__**>(&hStringClassName)); // internal method name subject to change post BUILD
if (FAILED(hr))
__cli_WinRTThrowError(hr); // internal method name subject to change post BUILD
String^ className = reinterpret_cast<String^>(hStringClassName);
ComPtr<IMetaDataDispenserEx> metadataDispenser; ComPtr<IMetaDataImport2> metadataImport; hr = MetaDataGetDispenser(CLSID_CorMetaDataDispenser, IID_IMetaDataDispenser, (LPVOID*)metadataDispenser.GetAddressOf());
if (FAILED(hr))
__cli_WinRTThrowError(hr); // internal method name subject to change post BUILD
HSTRING hStringFileName;
mdTypeDef typeDefToken;
hr = RoGetMetaDataFile(hStringClassName, metadataDispenser.Get(), &hStringFileName, &metadataImport, &typeDefToken);
if (FAILED(hr))
__cli_WinRTThrowError(hr); // internal method name subject to change post BUILD
String^ fileName = reinterpret_cast<String^>(hStringFileName);
HCORENUM hCorEnum = 0;
mdMethodDef methodDefs[2048];
ULONG countMethodDefs = sizeof(methodDefs);
hr = metadataImport->EnumMethods(&hCorEnum, typeDefToken, methodDefs, countMethodDefs, &countMethodDefs);
if (FAILED(hr))
__cli_WinRTThrowError(hr); // internal method name subject to change post BUILD
wchar_t methodName[1024];
ULONG countMethodName;
std::wstring strMethods;
Vector<String^>^ retVal = ref new Vector<String^>();
for (int i = 0; i < countMethodDefs; ++i)
{
countMethodName = sizeof(methodName);
hr = metadataImport->GetMethodProps(methodDefs[i], nullptr, methodName, countMethodName, &countMethodName, nullptr, nullptr, nullptr, nullptr, nullptr);
if (SUCCEEDED(hr))
{
methodName[ countMethodName ] = 0;
retVal->Append(ref new String(methodName));
}
}
return retVal;
}