---
name: "VistaIOExtractAttr"
section: "3"
platform: "linux"
package: "libvistaio-dev"
version: "1.2.19-3+b2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/VistaIOExtractAttr"
---

# VistaIOExtractAttr(3)

fetch and delete an attribute

## NAME

VistaIOExtractAttr - fetch and delete an attribute

## SYNOPSIS

```
VistaIOBoolean VistaIOExtractAttr (list, name, dict, repn, value, required)
VistaIOAttrList list;
VistaIOStringConst name;
VistaIODictEntry *dict;
VistaIORepnKind repn;
VistaIOPointer value;
VistaIOBoolean required;
```

## ARGUMENTS

- *list*

  **Specifies the list of attributes to be searched by name for the desired** **attribute.**

- *name*

  **Specifies the name of the desired attribute.**

- *dict*

  **May specify a dictionary to be used in recognizing a keyword** **stored as the attribute's value, or it may be** **NULL**

- *repn*

  **Specifies the representation in which the attribute value is to be**  **returned.**

- *value*

  **Specifies a location at which the attribute value is be returned.**

- *required*

  **Is** **TRUE** **if failure to find the attribute should be considered an error.**

## DESCRIPTION

**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)](/VistaIOdictionary/3.md) 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.)**

## RETURN VALUES

**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***.**

## SEE ALSO

[**VistaIOGetAttr**(3)](/VistaIOGetAttr/3.md), **VistaIOGetAttrValue**(3), **VistaIOLookupAttr**(3), **VistaIODeleteAttr**(3), [**VistaIOInsertAttr**(3)](/VistaIOInsertAttr/3.md),\
 [**VistaIOattribute**(3)](/VistaIOattribute/3.md), [**VistaIOdictionary**(3)](/VistaIOdictionary/3.md),

## NOTES

**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.**

## DIAGNOSTICS

- \`\`*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.**

## AUTHOR

**Art Pope \<pope@cs.ubc.ca\>**

**Adaption to vistaio: Gert Wollny \<gw.fossdev@gmail.com\>**