The IPropertySetStorage interface creates, opens, deletes, and enumerates property set storages that support instances of the IPropertyStorage interface. The IPropertyStorage interface manages a single property set in a property storage subobject; and the IPropertySetStorage interface manages the storage of groups of such property sets. Any file system entity can support IPropertySetStorage that is currently implemented in the COM compound file object.

The IPropertySetStorage and IPropertyStorage interfaces provide a uniform way to create and manage property sets, whether or not these sets reside in a storage object that supports IStorage. When called through an object supporting IStorage (such as structured and compound files) or IStream, the property sets created conform to the COM property set format, described in detail in Structured Storage Serialized Property Set Format. Similarly, properties written using IStorage to the COM property set format are visible through IPropertySetStorage and IPropertyStorage.

IPropertySetStorage methods identify property sets through a globally unique identifier (GUID) called a format identifier (FMTID). The FMTID for a property set identifies the property identifiers in the property set, their meaning, and any constraints on the values. The FMTID of a property set should also provide the means to manipulate that property set. Only one instance of a given FMTID may exist at a time within a single property storage.

When To Implement

Implement IPropertySetStorage to store persistent properties in an object. If you are using the COM compound files implementation, you can use the implementation on the compound file object created through a call to StgCreateStorageEx or StgOpenStorageEx.

When To Use

Call IPropertySetStorage methods to create, open, or delete one or more property sets, or to enumerate the property sets contained in this property set storage.

Methods

The IPropertySetStorage interface inherits the methods of the IUnknown interface.

In addition, IPropertySetStorage defines the following methods.

Remarks

Note  There is an exception to the above in The DocumentSummaryInformation and UserDefined property set. This property set is unique in that it may have two property set sections in a single underlying stream. This property set is described in The DocumentSummaryInformation and UserDefined Property Sets. The first section is the DocumentSummaryInformation property set. The second section is the UserDefined property set. Each section is identified by a unique format identifier (FMTID). For example, FMTID_DocSummaryInformation and FMTID_UserDefined property set. The fact that these two property sets can exist in a single stream affects the behavior of the IPropertySetStorage interface.

When IPropertySetStorage::Create is called to create the UserDefined property set, the first section is created automatically. Once the FMTID_UserDefinedProperties is created, FMTID_DocSummaryInformation need not be created, but can be operend with a call to IPropertySetStorage::Open. Creating the first section does not automatically create the second section and it is not possible to open both sections simultaneously.

Calling IPropertySetStorage::Delete, to delete the first section, causes both sections to be deleted. In other words, calling IPropertySetStorage::Delete with FMTID_DocSummaryInformation causes both that section and the FMTID_UserDefinedProperties section to be deleted. However, deleting the second section does not automatically delete the first section.

When IPropertySetStorage::Enum is used to enumerate property sets, the UserDefined property set is not enumerated.

Requirements

See Also

IPropertySetStorage-Compound File Implementation

IPropertySetStorage-NTFS File System Implementation

IPropertySetStorage-Stand-alone Implementation

IPropertyStorage

IEnumSTATPROPSETSTG

STATPROPSETSTG

PROPVARIANT

EnumAll Sample

Samples

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Build date: 11/12/2009