[Developers] Re: [CactusMaint] ActiveThorns docs bug (fwd)

[Jonathan Thornburg]

In bug #1943 I wrote:
>>> The Cactus Users' Guide section A3.2 "Parameter File Syntax",
>>> doesn't fully describe how ActiveThorns lines work.  In
>>> particular:
[[...]]
>>> * It should describe the (rather complicated!) rules
>>>   determining the orders in which thorns may or may not
>>>   appear in ActiveThorns lines.
>>
>> (If the rules for that last part are unclear, we should discuss them
>> on  developers at cactuscode.org .)

Erik commented:
> The rules seem to be straightforward: If a thorn needs some other
> thorns, then these other thorns must be activated before that thorn.

Or in the same ActiveThorns line -- if thorn B uses thorn A,
(so A must precede B) then Cactus currently allows
    ActiveThorns = "B A"
Again, I'm not sure if this is a bug or a feature, but I suspect
lots of existing par files depend on it (eg by having a single
monster ActiveThorns line listing a huge blob of thorns in quasirandom
order)...

But apart from that little detail, I agree with Erik.
In hindsight, my "rather complicated" phrase was a mistake --
the hard part is actually...

> What is complicated is figuring out these dependencies from scratch.
> What about a command line option to Cactus that prints all thorn
> dependencies for a single thorn, and the closure of that?

ciao,

-- 
-- Jonathan Thornburg <jthorn at aei.mpg.de>
    Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut),
    Golm, Germany, "Old Europe"     http://www.aei.mpg.de/~jthorn/home.html
    "Washing one's hands of the conflict between the powerful and the
     powerless means to side with the powerful, not to be neutral."
                                       -- quote by Freire / poster by Oxfam