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CoGetTreatAsClass function (combaseapi.h)

  • Article
  • 02/22/2024

Returns the CLSID of an object that can emulate the specified object.

Syntax

HRESULT CoGetTreatAsClass(
  [in]  REFCLSID clsidOld,
  [out] LPCLSID  pClsidNew
);

Parameters

[in] clsidOld

The CLSID of the object that can be emulated (treated as) an object with a different CLSID.

[out] pClsidNew

A pointer to where the CLSID that can emulate clsidOld objects is retrieved. This parameter cannot be NULL. If there is no emulation information for clsidOld objects, the clsidOld parameter is supplied.

Return value

This function can return the following values, as well as any error values returned by the CLSIDFromString function.

Return code Description
S_OK
 A new CLSID was successfully returned.
S_FALSE
 There is no emulation information for the clsidOld parameter, so the pClsidNew parameter is set to clsidOld.
REGDB_E_READREGDB
There was an error reading the registry.

Remarks

CoGetTreatAsClass returns the TreatAs entry in the registry for the specified object. The TreatAs entry, if set, is the CLSID of a registered object (an application) that can emulate the object in question. The TreatAs entry is set through a call to the CoTreatAsClass function. Emulation allows an application to open and edit an object of a different format, while retaining the original format of the object. Objects of the original CLSID are activated and treated as objects of the second CLSID. When the object is saved, this may result in loss of edits not supported by the original format. If there is no TreatAs entry for the specified object, this function returns the CLSID of the original object (clsidOld).

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 combaseapi.h (include Objbase.h)
Library Ole32.lib
DLL Ole32.dll

See also

CoTreatAsClass

Additional resources