IIndexableConcept::GetAt method (dbgmodel.h)

Article
02/22/2024

The GetAt method retrieves the value at a particular N-dimensional index from within the indexed object. An indexer of N-dimensions where N is the value returned from GetDimensionality must be supported. Note that an object may be indexable in different domains by different types (e.g.: indexable via both ordinals and strings). If the index is out of range (or could not be accessed), the method will return a failure; however, in such cases, the output object may still be set to an error object.

Syntax

HRESULT GetAt(
  IModelObject                *contextObject,
  ULONG64                     indexerCount,
  IModelObject                **indexers,
  _COM_Errorptr_ IModelObject **object,
  IKeyStore                   **metadata
);

Parameters

contextObject

The instance object (this pointer) which is being indexed is passed here.

indexerCount

The number of dimensions that the object is being indexed in.

indexers

An array (sized according to the indexerCount) of indices indicating where inside the instance object to access.

object

The value of the element at the specified indices is returned here. If the method fails, extended error information may be returned here as an error object.

metadata

Optional metadata about the indexed element may be returned here.

Return value

This method returns HRESULT which indicates success or failure.

Remarks

Example Implementation:

// Consider that we are pairing this with the same MyObjectIterator class 
// shown in the example snippet for IModelIterator::GetNext.
IFACEMETHOD(GetAt)(_In_ IModelObject *pContextObject, 
                   _In_ ULONG64 indexerCount, 
                   _In_reads_(indexerCount) IModelObject **ppIndexers, 
                   _COM_Errorptr_ **ppValue, 
                   _COM_Outptr_opt_result_maybenull_ IKeyStore **ppMetadata)
{
    HRESULT hr = S_OK;
    *ppValue = nullptr;
    if (ppMetadata != nullptr)
    {
        *ppMetadata = nullptr;
    }

    if (indexerCount != 1)
    {
        return E_INVALIDARG;
    }

    ComPtr<IModelObject> spValue;

    ULONG64 numElements;
    ComPtr<IModelObject> spNumElements;
    hr = pContextObject->GetKeyValue(L"NumElements", &spNumElements, nullptr));
    if (SUCCEEDED(hr))
    {
        VARIANT vtNumElements;
        hr = spNumElements->GetIntrinsicValueAs(VT_UI8, &vtNumElements));
        if (SUCCEEDED(hr))
        {
            VARIANT vtIdx;
            hr = ppIndexers[0]->GetIntrinsicValueAs(VT_UI8, &vtIdx));
            if (SUCCEEDED(hr))
            {
                if (vtIdx.ullVal >= vtNumElements.ullVal)
                {
                    return E_BOUNDS;
                }

                VARIANT vtValue;
                vtValue.vt = VT_UI8;
                vtValue.ullVal = vtIdx.ullVal + 10;
                hr = GetManager()->CreateIntrinsicObject(ObjectIntrinsic, 
                                                         &vtValue, 
                                                         &spValue);
            }
        }
    }

    if (SUCCEEDED(hr))
    {
        *ppValue = spValue.Detach();
    }

    return hr;
}

Requirements

Requirement	Value
Header	dbgmodel.h