IRootStorage interface

The IRootStorage 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 IStorage::Commit is guaranteed to not 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.

COM 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. This interface is also useful on older systems where limits on file handles can be exceeded.

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.

Members

The IRootStorage interface inherits from the IUnknown interface. IRootStorage also has these types of members:

• Methods

Methods

The IRootStorage interface has these methods.

Requirements

See also

IStorage

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