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IObjectContext::CreateInstance method (comsvcs.h)

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Creates an object using current object's context.

Syntax

HRESULT CreateInstance(
  [in]  REFCLSID rclsid,
  [in]  REFIID   riid,
  [out] LPVOID   *ppv
);

Parameters

[in] rclsid

The CLSID of the type of object to instantiate.

[in] riid

Any interface that's implemented by the object you want to instantiate.

[out] ppv

A reference to the requested interface on the new object. If instantiation fails, this parameter is set to NULL.

Return value

This method can return the following values.

Return code Description
S_OK
 The method completed successfully.
REGDB_E_CLASSNOTREG
 The component specified by clsid is not registered as a COM component.
E_OUTOFMEMORY
 There's not enough memory available to instantiate the object.
E_INVALIDARG
 The argument passed in the ppvObj parameter is invalid.
E_UNEXPECTED
 An unexpected error occurred. This can happen if one object passes its IObjectContext pointer to another object and the other object calls CreateInstance using this pointer. An IObjectContext pointer is not valid outside the context of the object that originally obtained it.

Remarks

CreateInstance creates a COM object. However, the object will have context only if its component is registered with COM+.

When you create an object by using CreateInstance, the new object's context is derived from the current object's IObjectContext and the declarative properties of the new object's component. The new object always executes within the same activity as the object that created it. If the current object has a transaction, the transaction attribute of the new object's component determines whether the new object executes within the scope of that transaction.

If the component's transaction attribute setting either requires a transaction or supports transactions, the new object inherits its creator's transaction. If the component's transaction attribute requires a new transaction, COM+ initiates a new transaction for the new object. If the component's transaction attribute does not support transactions, the new object doesn't execute under any transaction.

CreateInstance always returns the IUnknown interface on the newly instantiated object. You should immediately cast the returned value to the interface through which you want to communicate with the new object. The interface ID you pass in the riid parameter does not need to be the same interface as the one to which you cast the returned value, but it must be an interface that is implemented by the object you are instantiating.

Requirements

Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header comsvcs.h

See also

IObjectContext