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IPersistStorage::InitNew

  • Artigo

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This method initializes a new object, providing a pointer to the storage to be used for the object.

Syntax

HRESULT InitNew( 
  IStorage* pStg
);

Parameters

  • pStg
    [in] IStorage pointer to the new storage object to be initialized.

    The container creates a nested storage object in its storage object (see IStorage::CreateStorage). Then, the container calls the WriteClassStg function to initialize the new storage object with the object class identifier (CLSID).

Return Value

The following table shows the return values for this method.

Value Description

S_OK

The new storage object was successfully initialized.

CO_E_ALREADYINITIALIZED

The object has already been initialized by a previous call to either the IPersistStorage::Load method or the IPersistStorage::InitNew method.

E_OUTOFMEMORY

The storage object was not initialized due to a lack of memory.

E_FAIL

The storage object was not initialized for some reason other than a lack of memory.

Remarks

A container application can call this method when it needs to initialize a new object, for example, with an InsertObject command.

An object that supports the IPersistStorage interface must have access to a valid storage object at all times while it is running. This includes the time just after the object has been created but before it has been made persistent.

The object's container must provide the object with a valid IStorage pointer to the storage during this time through the call to IPersistStorage::InitNew.

Depending on the container's state, a temporary file might have to be created for this purpose.

If the object wants to retain the IStorage instance, it must call the IUnknown::AddRef method to increment its reference count.

After the call to IPersistStorage::InitNew, the object is in either the loaded or running state.

For example, if the object class has an in-process server, the object will be in the running state. However, if the object uses the default handler, the container's call to InitNew only invokes the handler's implementation, which does not run the object.

Later, if the container runs the object, the handler calls the IPersistStorage::InitNew method for the object.

To determine whether the platform supports this interface, see Determining Supported COM APIs.

Notes to Callers

Rather than calling IPersistStorage::InitNew directly, you typically call the OleCreate helper function that does the following:

  1. Calls the CoCreateInstance function to create an instance of the object class
  2. Queries the new instance for the IPersistStorage interface
  3. Calls the IPersistStorage::InitNew method to initialize the object

The container application should cache the IPersistStorage pointer to the object for use in later operations on the object.

Notes to Implementers

An implementation of IPersistStorage::InitNew should initialize the object to its default state, taking the following steps:

  1. Pre-open and cache the pointers to any streams or storages that the object will need to save itself to this storage.
  2. Call IPersistStorage::AddRef and cache the storage pointer that is passed in.
  3. Call the WriteFmtUserTypeStg function to write the native clipboard format and user type string for the object to the storage object.
  4. Set the dirty flag for the object.

The first two steps are particularly important for ensuring that the object can save itself in low memory situations. Pre-opening and holding onto pointers to the stream and storage interfaces guarantee that a save operation to this storage will not fail due to insufficient memory.

Your implementation of this method should return the CO_E_ALREADYINITIALIZED error code if it receives a call to either the IPersistStorage::InitNew method or the IPersistStorage::Load method after it is already initialized.

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

See Also

Reference

WriteClassStg
IPersistStorage
IStorage
IStorage::CreateStorage
IPersistStorage::Load
IUnknown::AddRef