[jira] [Commented] (DAFFODIL-2352) dfdl:newVariableInstance with non-constant defaultValue fails

["Mike Beckerle (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DAFFODIL-2352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17130931#comment-17130931 ] 

Mike Beckerle commented on DAFFODIL-2352:
-----------------------------------------

This style of using dfdl:newVariableInstance with a defaultValue to both create the new instance and provide the formula for evaluating its value, all in one statement, is probably the preferred idiom. (versus two statements - a second statement to set the value). 


> dfdl:newVariableInstance with non-constant defaultValue fails
> -------------------------------------------------------------
>
>                 Key: DAFFODIL-2352
>                 URL: https://issues.apache.org/jira/browse/DAFFODIL-2352
>             Project: Daffodil
>          Issue Type: Bug
>          Components: Back End
>    Affects Versions: 2.6.0
>            Reporter: Steve Lawrence
>            Priority: Major
>
> If we have a schema with newVariableInstance that uses a non-constant DFDL expression for the default value, that default value is never set. For example:
> {code:xsd}
> <xs:sequence>
>   <xs:annotation>
>     <xs:appinfo source="http://www.ogf.org/dfdl/">
>       <dfdl:newVariableInstance ref="foo" defaultValue="{ /some/non/constant/thing }" />
>     </xs:appinfo>
>   </xs:annotation>
>   <xs:element name="fooValue" type="xs:int" dfdl:inputValueCalc="{ $foo }" />            </xs:sequence>
> {code}
> When the inputValueCalc expressoin is evaluated, we fail with the error
> {code}
> Runtime Schema Definition Error: Variable Error: Variable map (runtime): variable foo has no value. It was not set, and has no default value.
> {code}
> According to the spec:
> {code}
> If a default value is specified this initial value of the instance will be set when the instance is created
> {code}
> So we are likely just missing the logic to evaluate and set the default when when we create the new VariableInstacne.
> This might also affect dfdl:defineVariable as well, which is allowed to also have expressions as the defaultValue, as long as the expression doesn't reference the infoset and only other variables.



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