Re: [xmile] macros + filters

[Bobby Powers <bobbypowers@gmail.com>]

Hi Will,

So I agree about the level of effort/prioritization.  I guess my
question is can we create a v1 XMILE spec that supports 90% of SD
models without macros?  I think the answer is yes.  If others feel
differently - what do we specifically need from macros to support
80-90% of SD models?

yours,
Bobby

On Mon, Jun 9, 2014 at 2:58 PM, Will Glass-Husain <wglass@forio.com> wrote:
> Hi Bobby,
>
> Good points.    My take is that the primary benefit of implementing macros
> is to add new functions required by a mdeol that aren't supported.  A
> simpler macro functionality could meet that need.
>
> From an implementation point of view, there's 4 levels of macros
> 1.  simple macros (no variables, no recursion).  This could be implemented
> by text substitution when importing a model.
> 2.  macros with internal variables, no recursion.  This could be implemented
> by adding new variables when importing a model
> 3.  macros specifying custom building blocks.   Seems more complex to
> implement.
> 4.  macros with recursion.  For  most software would need to implement new
> features to the core computation engine to make this work.
>
> I'm fine with implementing 1-2 and possibly #3.  But #4 above is a lot more
> work.  I'd be ok with prohibiting recursion.  (the simplest way to limit
> this would be to prohibit the use of macros in other macros).
>
> WILL
>
>
> On Mon, Jun 9, 2014 at 9:58 AM, Bobby Powers <bobbypowers@gmail.com> wrote:
>>
>> Hello fellow TC members,
>>
>> I missed the last meeting, so I apologize if this was addressed
>> (although I don't see it in the minutes), but I'm just looking at the
>> Macro + filters that was recently added to the OASIS spec, and have
>> some concerns.
>>
>> Part of it is that AFAIK we haven't discussed macros at all.  There
>> are a lot of hairy cases with macros, especially around recursion and
>> separate sim-specs, and I'm not sure if parts of this have been
>> implemented.  I added the "FACT" example to a STELLA model, and it was
>> unable to simulate.  I think part of the rationale behind macros is
>> for Vensim compatibility, but I had thought Bob mentioned at one point
>> there were extensions needed for that.  So I'm wary of having
>> complicated parts of the spec that currently have no implementation
>> when we don't even know if they will meet Ventana's needs.
>>
>> I have similar concerns about the "modifying stock and flow behavior"
>> section.  It is quite complicated to me, hard to follow, and adds a
>> LOT of overhead for people wanting to implement the spec.  Can we get
>> a clarification - does isee currently support everything listed in
>> that section?  If not, let us please remove it from v1 of the spec.
>> An example of the problem: "The existence of such a macro does not
>> rule out another macro that operates on the stock instead of its
>> outflows. Such a macro would not have the applyto option. In fact, any
>> stock or flow option can implement three filters: one for the stock or
>> flow itself and one for each of the two applyto options".  I think
>> that is confusing at best - but is also unspecified behavior.  In what
>> order to multiple filters run is my first question.
>>
>> yours,
>> Bobby
>>
>> ---------------------------------------------------------------------
>> To unsubscribe from this mail list, you must leave the OASIS TC that
>> generates this mail.  Follow this link to all your TCs in OASIS at:
>> https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
>>
>
>
>
> --
> William Glass-Husain   /forio  |  +1 (415) 440 7500 x89  |  forio.com
>