VistaIOExtractAttr(3) fetch and delete an attribute


VistaIOBoolean VistaIOExtractAttr (list, name, dict, repn, value, required)

VistaIOAttrList list; VistaIOStringConst name; VistaIODictEntry *dict; VistaIORepnKind repn; VistaIOPointer value; VistaIOBoolean required;


Specifies the list of attributes to be searched by name for the desired attribute.
Specifies the name of the desired attribute.
May specify a dictionary to be used in recognizing a keyword stored as the attribute's value, or it may be NULL
Specifies the representation in which the attribute value is to be returned.
Specifies a location at which the attribute value is be returned.
Is TRUE if failure to find the attribute should be considered an error.


VistaIOExtractAttr locates the first attribute named name in list, removing it if found and returning its value.

If a dictionary, dict, has been provided and the attribute's value is stored as a character string, the routine determines whether the string is a keyword defined in the dictionary. If so, it uses the value associated with that keyword rather than the attribute's original value. (See the VistaIOdictionary(3) manual page.)

The value obtained directly from the attribute, or indirectly via the dictionary, is converted to the representation repn and then stored at the location pointed to by value. The repn argument may have any VistaIORepnKind value or any of the values returned by VistaIORegisterType(3). However, an attribute value that is a string can only be returned as a string or a number, and other attribute values can only be returned in the representation with which they are stored. (The VistaIOGetAttrRepn(3) macro can be used to determine an attribute value's representation.)


VistaIOExtractAttr returns FALSE if required is TRUE and no attribute named name is found. If also returns FALSE if an attribute is found but its value cannot be converted to the desired representation. Otherwise, VistaIOExtractAttr returns TRUE while perhaps modifying the list list and storing a value at value.


VistaIOExtractAttr is meant for use with attribute lists representing sets, in which each attribute name occurs at most once. If list contains multiple attributes named name, only the first is located.

The value argument must point to sufficient storage to contain a value of the representation requested. Neither the routine nor the C compiler can automatically check that this is so.

If a string value is returned, it will be in newly-allocated storage. Release the storage with VistaIOFree(3) when done with the string.


``name attribute missing.''
No attribute named name could be found, and required is TRUE
``name attribute has bad value.''
The attribute was found, but its value cannot be converted to the desired representation.


Art Pope <[email protected]>

Adaption to vistaio: Gert Wollny <[email protected]>