OleSetAutoConvert

Tags an object for automatic conversion to a different class when the object is loaded.

HRESULT OleSetAutoConvert(

REFCLSID clsidOld,	//CLSID to be converted
REFCLSID clsidNew	//New CLSID after conversion
);

Parameters
clsidOld

Specifies the CLSID of the object class to be converted.

clsidNew

Specifies the CLSID of the object class that should replace clsidOld. This new CLSID replaces any existing auto-conversion information in the registration database for clsidOld. If this value is CLSID_NULL, any existing auto-conversion information for clsidOld is removed from the registration database.

Return Values
S_OK

Indicates the object was tagged successfully.

REGDB_E_CLASSNOTREG

Indicates the CLSID is not properly registered in the registration database.

REGDB_E_READREGDB

Indicates error reading from the registration database.

REGDB_E_WRITEREGDB

Indicates error writing to the registration database.

REGDB_E_KEYMISSING

Indicates cannot read a key from the registration database.

E_OUTOFMEMORY

Indicates the auto-conversion cannot be completed due to a lack of memory.

E_INVALIDARG

Indicates one or more arguments are invalid.

E_UNEXPECTED

Indicates an unexpected error occurred.

Comments
The OleSetAutoConvert function sets the entry for AutoConvertTo entry for clsidOld in the registration database. This function does no validation of whether an appropriate registration database entry for clsidNew currently exists. When it is called, the OleSetAutoConvert function records the new CLSID for the object under the AutoConvertTo subkey in the registration database for clsidOld.

Object conversion means that the object is permanently associated with a new CLSID. Automatic conversion is typically specified by the setup program for a new version of an object application, so that objects created by its older versions can be automatically updated. You can write the setup program to tag a class of objects for automatic conversion to a different class of objects.

For example, a new version of a spreadsheet application may need to convert spreadsheets that were created with earlier versions of the application. These earlier version spreadsheet objects have a different CLSID than the new version. The setup program for the new version of the spreadsheet application tags objects in the registration database that have the old CLSID so they are automatically updated when they are loaded.

When installing a new CLSID, setup programs may call OleSetAutoConvert for various clsidOld values for older versions of their applications. They also should call OleSetAutoConvert, specifying the new class as the clsidOld parameter, and setting the clsidNew parameter to CLSID_NULL to remove any existing conversion for the new class.

The OleSetAutoConvert function creates the required entry in the registration database. These entries appear in the registration database as subkeys of the CLSID key:

CLSID\{clsid}=MainUserTypeName\AutoConvertTo = clsid