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IPersistStorage interface

Enables a container application to pass a storage object to one of its contained objects and to load and save the storage object. This interface supports the structured storage model, in which each contained object has its own storage that is nested within the container's storage.

When to implement

Any object that can be embedded in a container must implement the IPersistStorage interface. This interface is one of the primary interfaces for a compound document object. Embeddable objects must also implement the IOleObject and IDataObject interfaces.

The OLE default handler for embedded objects provides an implementation of the IPersistStorage interface that is used when the object is in the loaded state. Similarly, the OLE default link handler provides an IPersistStorage implementation that manages storage for a linked object. These default handlers both interact with the OLE default cache implementation, which has its own IPersistStorage implementation.

If you are providing a custom embedding or link handler for your objects, the handler must include an implementation of IPersistStorage. You can delegate calls to the default handler so you can take advantage of the default cache implementation.

When to use

When an OLE container creates a new object, loads an existing object from storage, or inserts a new object in a clipboard or a drag-and-drop operation, the container uses the IPersistStorage interface to initialize the object and put it in the loaded or running state. When an object is loaded or running, an OLE container calls other IPersistStorage methods to instruct the object to perform various save operations or to release its storage.

Typically, applications use helper functions such as OleLoad or OleCreate, rather than calling the Load or InitNew methods directly. Similarly, applications typically call the OleSave function rather than calling Save directly.

Members

The IPersistStorage interface inherits from IPersist. IPersistStorage also has these types of members:

Methods

The IPersistStorage interface has these methods.

MethodDescription
HandsOffStorage

Instructs the object to release all storage objects that have been passed to it by its container and to enter HandsOff mode.

InitNew

Initializes a new storage object.

IsDirty

Determines whether an object has changed since it was last saved to its current storage.

Load

Loads an object from its existing storage.

Save

Saves an object, and any nested objects that it contains, into the specified storage object. The object enters NoScribble mode.

SaveCompleted

Notifies the object that it can write to its storage object.

 

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

ObjIdl.h

IDL

ObjIdl.idl

IID

IID_IPersistStorage is defined as 0000010a-0000-0000-C000-000000000046

See also

OleCreate
OleLoad
OleSave

 

 

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