Subject: [forces] LFB class Inheritance

From: Jamal Hadi Salim <[email-masked]>
Date: Tue, 25 Feb 2014 07:03:35 -0500

We've run into a small (accidental) problem while using inheritance when
someone changed a derived from structure in the parent LFB.

5812 section 3.2.8 says when specifying inheritance of an LFB class,
that i need to specify not only the derived-from parent LFB class but
also the version of the parent I am inheriting.
The schema doesnt let me - what am i missing?

cheers,
jamal

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From: Joel <[email-masked]>
Date: Tue, 25 Feb 2014 12:23:04 -0500

I think this is a case where we found ourselves with a problem.
Specifying the version number for the base is awkward, and often likely 
to be unneeded.

However, leaving it out creates the potential for collision, and thus 
failure.  (Image base class Av1 uses IDs 1-10.  class Bv1 is derived 
from A, and uses IDs 11 and 12.  Now we do a new version of A, and Av2 
uses ID 11.  B can not be derived from Av2.)

We appear to have simply dropped the ball on this.  (Note to self: use 
issue trackers so as not to lose track of this sort of thing while 
revising documents.)

Yours,
Joel

On 2/25/14, 7:03 AM, Jamal Hadi Salim wrote:
> _______________________________________________
> forces mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/forces
>

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From: "Haleplidis Evangelos" <[email-masked]>
Date: Tue, 25 Feb 2014 19:48:43 +0200

Greetings Jamal and Joel,

I agree with Joel that there are potential collision issues and thus the
version has to be included.
I think we can easily address this issue within the model extension draft.

Regards,
Evangelos Haleplidis.

> -----Original Message-----
> From: forces [mailto:[email-masked]] On Behalf Of Joel
> Sent: Tuesday, February 25, 2014 7:23 PM
> To: Jamal Hadi Salim; [email-masked]
> Subject: Re: [forces] LFB class Inheritance
> 
> > We've run into a small (accidental) problem while using inheritance
> > when someone changed a derived from structure in the parent LFB.
> >

---

From: Jamal Hadi Salim <[email-masked]>
Date: Wed, 26 Feb 2014 06:29:42 -0500

On Tue, Feb 25, 2014 at 12:23 PM, Joel <[email-masked]> wrote:
> Specifying the version number for the base is awkward, and often likely to
> be unneeded.
>
> failure.  (Image base class Av1 uses IDs 1-10.  class Bv1 is derived from A,
> and uses IDs 11 and 12.  Now we do a new version of A, and Av2 uses ID 11.
> B can not be derived from Av2.)
>

Precisely the problem we ran into;-> Our compiler assumed we were
overriding ID 11
from the newly minted Av2 (hence my earlier comment the discovery was
"accidental").

> We appear to have simply dropped the ball on this.  (Note to self: use issue
> trackers so as not to lose track of this sort of thing while revising
> documents.)
>

Would the suggestion from Evangelos to introduce this in the new model
extensions suffice
or do we still need an issue tracker entry?

cheers,
jamal

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From: Joel <[email-masked]>
Date: Wed, 26 Feb 2014 08:46:29 -0500

For this issue, covering it in the model extensions draft is the right 
answer.

The issue tracker point was more general (and broader than ForCES.)
We have an issue tracker with the WG.  We could use it to record this 
sort of issue.  And then check it to make sure we actually dealt with 
all the issues.

Yours,
Joel