RoGetParameterizedTypeInstanceIID function (roparameterizediid.h)

Article
10/13/2021

Computes the interface identifier (IID) of the interface or delegate type that results when a parameterized interface or delegate is instantiated with the specified type arguments.

Syntax

HRESULT RoGetParameterizedTypeInstanceIID(
                  UINT32                     nameElementCount,
  [in]            PCWSTR                     *nameElements,
  [in]            const IRoMetaDataLocator & metaDataLocator,
  [out]           GUID                       *iid,
  [out, optional] ROPARAMIIDHANDLE           *pExtra
);

Parameters

nameElementCount

Type: UINT32

Number of elements in nameElements.

[in] nameElements

Type: PCWSTR*

A parsed Windows Runtime type name, as returned by the RoParseTypeName function. For example, "Windows.Foundation.Collections.IVector`1", and "N1.N2.IFoo".

[in] metaDataLocator

Type: const IRoMetaDataLocator

A callback to use for resolving metadata.

An implementation should use the RoGetMetaDataFile function to discover the necessary metadata (.winmd) file and examine the metadata to determine the necessary type information. Because the RoGetMetaDataFile function does not cache results, locators should cache the results as appropriate for the programming model being implemented.

[out] iid

Type: GUID*

The IID of the interface or delegate that corresponds with nameElements.

[out, optional] pExtra

Type: ROPARAMIIDHANDLE*

Handle to the IID that corresponds with nameElements.

Return value

Type: HRESULT

Return code	Description
S_OK	The call was successful.
E_OUTOFMEMORY	Insufficient memory available to complete the task.
E_INVALIDARG	The wrong number of type arguments are provided for a parameterized type.

A failure may also occur if a type is inappropriate for the context in which it appears.

Remarks

The RoGetParameterizedTypeInstanceIID function is for use by programming language implementers.

This function is stateless. The metaDataLocator argument is not preserved between calls and may be released as soon as the call returns.

The RoGetParameterizedTypeInstanceIID function does not perform deep semantic analysis. For instance, if IRoSimpleMetaDataBuilder specifies that a structure contains an interface pointer, this function returns success, even though such metadata is semantically invalid. The value of the returned IID is unspecified in such cases.

This function may recursively invoke the metadata locator provided as an argument.

If a call to the IRoSimpleMetaDataBuilder function fails, this function will return that failure code.

Examples


#include <stdlib.h>
#include <windows.h>
#include <winrt/paraminstanceapi.h>

HRESULT ExampleMetadataLocator(
    PCWSTR name, 
    IRoSimpleMetaDataBuilder& builder)
{
    if (wcscmp(L"Example.IParam`1", name) == 0)
    {
        GUID piidParam= { /* 22046e87-28b5-4c53-9804-bc69f6ee0299 */
            0x22046e87,
            0x28b5,
            0x4c53,
            {0x98, 0x04, 0xbc, 0x69, 0xf6, 0xee, 0x02, 0x99}
        };
        builder.SetParameterizedInterface(piidParam, 1);
    }
    else if (wcscmp(L"Example.InterfaceGroup", name) == 0)
    {
        builder.SetInterfaceGroupSimpleDefault(name, L"Example.IFoo", nullptr);
    }
    else if (wcscmp(L"Example.IFoo", name) == 0)
    {
        GUID iidFoo = { /* f7f968c2-b1d8-47e0-98db-1b04f2bba657 */
            0xf7f968c2,
            0xb1d8,
            0x47e0,
            {0x98, 0xdb, 0x1b, 0x04, 0xf2, 0xbb, 0xa6, 0x57}
        };
        builder.SetWinRtInterface(iidFoo);
    }
    return E_ABORT;
}

int main()
{
    // example, compute IID
    GUID iidResult;
    PCWSTR names = { L"Example.IParam`1", L"Example.InterfaceGroup" };
    HRESULT hr = RoGetParameterizedTypeInstanceIID(
        2,
        names,
        Ro::Locator(&ExampleMetadataLocator),
        &iidResult);
}

Requirements

Requirement	Value
Minimum supported client	Windows 8 [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2012 [desktop apps \| UWP apps]
Target Platform	Windows
Header	roparameterizediid.h
DLL	Api-ms-win-core-winrt-roparameterizediid-l1-1-0.dll

Share via