IRootStorage
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4/8/2010
This interface contains a single method that switches a storage object to a different underlying file and saves the storage object to that file.
The save operation occurs even with low memory conditions and uncommitted changes to the storage object.
A subsequent call to the IStorage::Commit method is guaranteed not to consume additional memory.
When to Implement
Storage objects that are based on a file should implement IRootStorage in addition to the IStorage interface. For storage objects that are not file-based, this interface is not necessary.
OLE provides an implementation of a storage object, including the IRootStorage interface, as part of its compound file implementation.
When to Use
The primary use for the IRootStorage interface is to save a storage object to a file during low memory conditions. Typically, the container application calls the IRootStorage interface to switch to a new file.
If you have an IStorage pointer to a compound file object, you can call IStorage::QueryInterface with IID_IRootStorage to obtain a pointer to the IRootStorage interface.
Methods
The following table shows the method for this interface.
| Method | Description |
|---|---|
Copies the file underlying this root storage object, then associates this storage with the copied file. |
Remarks
To determine whether the platform supports this interface, see Determining Supported COM APIs.
Requirements
| Header | objidl.h, objidl.idl |
| Library | ole32.lib, uuid.lib |
| Windows Embedded CE | Windows CE 2.0 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |