Thanks for the link. I agree with a number of items you have here as being useful. It seems like the best place to put something would be under "Allowing some DFDL properties to Coexist with IVC". The first paragraph could end with: Also, the default property does not conflict and allows the element to not be required during unparse.

I've also hit the problem of not having array variables and this seems useful as well as parse-time forward reference.

Regards,

Bradd Kadlecik
z/TPF Development

Phone: 1-845-433-1573
E-mail: braddk@us.ibm.com
2455 South Rd
Poughkeepsie, NY 12601-5400
United States

Mike Beckerle ---09/25/2019 12:06:09 PM---Daffodil project has been building up an experience document about inputValueCalc, outputValueCalc,

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: Bradd Kadlecik <braddk@us.ibm.com>
Cc: DFDL-WG <dfdl-wg@ogf.org>
Date: 09/25/2019 12:06 PM
Subject: [EXTERNAL] Re: [DFDL-WG] DFDL inputValueCalc restrictions

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

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

On Wed, Sep 25, 2019 at 11:49 AM Bradd Kadlecik <braddk@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@us.ibm.com	2455 South Rd Poughkeepsie, NY 12601-5400 United States

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