IPropertyBag::Write Method

---

Asks the property bag to save the named property in a caller-initialized VARIANT.

Syntax

HRESULT Write(
    LPCOLESTR pszPropName, 
    VARIANT *pVar
);

Parameters

pszPropName

[in] Address of a string containing the name of the property to write. This cannot be NULL.

pVar

[in] Address of the caller-initialized VARIANT that holds the property value to save. The caller owns this VARIANT and is responsible for all of its allocations. That is, the property bag itself does not attempt to free data in the VARIANT.

Return Value

Returns one of the following values:

S_OK	The property bag successfully saved the requested property.
E_FAIL	There was a problem writing the property. It is possible that the property bag is unable to save a particular VARIANT type.
E_POINTER	The address in pszPropName or pVar is not valid (such as NULL). The caller must supply both.

Remarks

The Write method asks the property bag to save the property named with pszPropName using the type and value in the caller-initialized VARIANT in pVar. In some cases, the caller may be asking the property bag to save another object—such as when pVar->vt is VT_UNKNOWN. In such cases, the property bag queries this object pointer for a persistence interface, such as IPersistStream or IPersistPropertyBag, and has that object save its data as well. Usually this results in the property bag having some byte array for this object, which can be saved as encoded text (hexadecimal string, MIME, and so on). When the property bag is later used to reinitialize a control, the client that owns the property bag must re-create the object when the caller asks for it, initializing that object with the previously saved bits.

This allows very efficient persistence operations for Binary Large Object (BLOB) properties, like a picture, where the owner of the property bag itself directly asks the picture object (managed as a property in the control being saved) to save into a specific location. This avoids potential extra copy operations that would be involved with other property-based persistence mechanisms.

E_NOTIMPL is not a valid return code because any object implementing this interface must support the entire functionality of the interface.

See Also

IPropertyBag::Read