CoGetInstanceFromFile function (objbase.h)

Creates a new object and initializes it from a file using IPersistFile::Load.

Syntax

HRESULT CoGetInstanceFromFile(
  [in, optional] COSERVERINFO *pServerInfo,
  [in, optional] CLSID        *pClsid,
  [in, optional] IUnknown     *punkOuter,
  [in]           DWORD        dwClsCtx,
  [in]           DWORD        grfMode,
  [in]           OLECHAR      *pwszName,
  [in]           DWORD        dwCount,
  [in, out]      MULTI_QI     *pResults
);

Parameters

[in, optional] pServerInfo

A pointer to a COSERVERINFO structure that specifies the computer on which to instantiate the object and the authentication setting to be used. This parameter can be NULL, in which case the object is instantiated on the current computer, at the computer specified under the RemoteServerName registry value for the class, or at the computer where the pwszName file resides if the ActivateAtStorage value is specified for the class or there is no local registry information.

[in, optional] pClsid

A pointer to the class identifier of the object to be created. This parameter can be NULL, in which case there is a call to GetClassFile, using pwszName as its parameter to get the class of the object to be instantiated.

[in, optional] punkOuter

When non-NULL, indicates the instance is being created as part of an aggregate, and punkOuter is to be used as the pointer to the new instance's controlling IUnknown. Aggregation is not supported cross-process or cross-computer. When instantiating an object out of process, CLASS_E_NOAGGREGATION will be returned if punkOuter is non-NULL.

[in] dwClsCtx

Values from the CLSCTX enumeration.

[in] grfMode

Specifies how the file is to be opened. See STGM Constants.

[in] pwszName

The file used to initialize the object with IPersistFile::Load. This parameter cannot be NULL.

[in] dwCount

The number of structures in pResults. This parameter must be greater than 0.

[in, out] pResults

An array of MULTI_QI structures. Each structure has three members: the identifier for a requested interface (pIID), the location to return the interface pointer (pItf) and the return value of the call to QueryInterface (hr).

Return value

This function can return the standard return value E_INVALIDARG, as well as the following values.

Remarks

CoGetInstanceFromFile creates a new object and initializes it from a file using IPersistFile::Load. The result of this function is similar to creating an instance with a call to CoCreateInstanceEx, followed by an initializing call to IPersistFile::Load, with the following important distinctions:

• Fewer network round trips are required by this function when instantiating an object on a remote computer.
• In the case where dwClsCtx is set to CLSCTX_REMOTE_SERVER and pServerInfo is NULL, if the class is registered with the ActivateAtStorage sub-key or has no associated registry information, this function will instantiate an object on the computer where pwszName resides, providing the least possible network traffic.

Requirements

See also

CLSCTX

CoCreateInstanceEx

CoGetInstanceFromIStorage