[DFDL-WG] DFDL inputValueCalc restrictions

[Mike Beckerle]

Daffodil project has been building up an experience document about
inputValueCalc, outputValueCalc, and hidden groups. The draft is on our
wiki here:

*https://s.apache.org/daffodil-experience-with-computed-elements*
<https://s.apache.org/daffodil-experience-with-computed-elements>

This will get finalized into an OGF Experience document and a number of
changes/corrections to the DFDL spec will come out of it I expect.

We already have identified that disallowing IVC and OVC on the same element
is unnecessary and sometimes you want this. Your case with default values
sounds similar.

We can incorporate your contribution to the experience document. Take a
look and see if the existing discussion can just be enhanced with a
sentence about also allowing default on an IVC element. If so I can edit
and add it there.

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are
subject to the OGF Intellectual Property Policy
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On Wed, Sep 25, 2019 at 11:49 AM Bradd Kadlecik <braddk at us.ibm.com> wrote:

> Hello,
>
> I have one item I'd like to discuss at some point regarding inputValueCalc
> and not allowing the default property to be specified. I have a use case
> where the default property would be useful for unparse. It makes perfect
> sense to not allow it for outputValueCalc however.
>
> The use case is in forming a connection between an inputValueCalc element
> and an outputValueCalc element where the incoming document might not
> contain the inputValueCalc element for unparse and a default value would be
> desired for the outputValueCalc use. This is an item our customers using
> DFDL would like to make use of but don't want to require the element to
> always exist for unparse.
>
> Regards,
>
> *Bradd Kadlecik*
> z/TPF Development
> ------------------------------
> *Phone:* 1-845-433-1573
> *E-mail:* *braddk at us.ibm.com* <braddk at us.ibm.com>
> 2455 South Rd
> Poughkeepsie, NY 12601-5400
> United States
>
>
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