clarify: handling of links later activated.

Joachim Euchner (joe@prz.tu-berlin.de)
Thu, 06 Nov 1997 12:18:35 +0100

Hello All,

first of all, a big thanks and big appreciation
to Guido and his Crew, for giving the
the test-applictions to us all.

yesterday, we played around with these apps,
and we found the following problem:

in Scene ivar0/scene1:
the two links, one activating the other.

{:IntegerVar
1
:InitiallyActive true
:OrigValue 100
}

{:Link 11
...
:EventSource 1
:EventType TestEvent
:EventData True
...
:LinkEffect
(
...
:Activate (21)
...
)
}

{:Link 21
:InitiallyActive false
...
:EventSource 1
:EventType TestEvent
:EventData True
...
:LinkEffect
(
...
)
}

what happens, when Link 11 fires?
well, link 21 will be activated.
For this see: 13.3: Activation,
2. Make the Link object receptive to events that
fulfil its LinkCondition.

good. we append this link to the link-register of Variable 1,
still only caused by firing Link 11. When having fired Link 11,
we look if there are more Links. And, whow, we have a new Link in the
List, namely Link 21. And, whow, it matches all conditions, so
lets fire it. - And this is how the mess begins.

Ok, its perfectly clear what was intended by the implementer
of the scene. On the other hand, it is nowhere stated
(at least to my knowledge) in the standard, that Links
later made known to the Link object, shall be ignored.

Naturally, this is no Problem to implement. Actually
I patched that, just to see the afore mentioned Application
running fine.

If this is a too stupid point, please forgive me for
occupying your attention.

thanx, and greetings
from Joe.

-- 
Joachim Euchner
Prozessrechnerverbund-Zentrale                            
Sekr.: MA 073, FSP-PV 
Technische Universitaet Berlin      
Str. d. 17. Juni 136, 
10623   Berlin, Deutschland          
Phone: [(+49|0)30] 314 21700
Fax:   [(+49|0)30] 314 21114                                    
Email: joe@prz.tu-berlin.de           
www:   www.prz.tu-berlin.de/~joe