Zugg Software :: View topic

Posted: Fri Sep 15, 2006 6:59 pm

I am proposing a change to Expression Triggers in CMUD, but I want to get feedback from people on this before I change it (which means I'll be posponing this until v1.07).

In zMUD, Expression Triggers are tested and executed each time *any* variable changes. For example:

Posted: Fri Sep 15, 2006 7:35 pm

I don't remember running into any issues with this trigger firing pattern, but I don't write too many complex scripts. I do like that this proposed behavior will put zScript in line with mainstream languages.

Wizard Joined: 11 Jul 2002 Posts: 1265 Location: USA

I would love the change. Very Happy

In my expression triggers in Zmud I would always test for a change I made the first time the trigger fired. IE if this is the first time it fires again don't do anything.

The double triggering always bugged me but it never managed to stop me Twisted Evil

Beginner Joined: 21 Jun 2003 Posts: 11 Location: USA

That would rock. I use to use expression triggers to do multiple things for me, but if another variable was being used it would cause the expression triggers to go freak out, sounds like this would be a great fix.

Apprentice Joined: 29 Jun 2001 Posts: 198 Location: USA

I would have to agree as well. This would solve some issues with expression triggers.

Posted: Sat Sep 16, 2006 12:05 am

Seems pretty unanimous. Implementing Expression Triggers in this way is easy in CMUD, so I'm going ahead with the change.

Posted: Sun Sep 17, 2006 4:25 am

Better that way for me too.

So long as:
#TRIGGER (@var=1000) {#SH Var is 1000!}

If I then type in the following three commands, the message "Var is 1000!" is currently (zmud) only displayed once
var=500
var=1000
var=1000

Please keep it that way (that is to say, that if the variable already has the value that you are attempting to set it to, then this attempt does not register as a changing value, not causing the trigger to fire.

I use expression triggers to make decisions about variables set by a prompt trigger. This is better for system speed than using #IF statements in the prompt trigger, since the expression trigger is not evaluated every line, but only when the actual variable value in question changes.

Posted: Sun Sep 17, 2006 4:57 am

Yep, that's correct. It only fires once (the first time you set var=1000)

Wizard Joined: 14 Aug 2004 Posts: 1269

Am I right in thinking that the new expression triggers would be more efficient, performance-wise, than the old ones? I don't know if this was a factor before - I had never looked at them, let alone used them. But it seems like the old way could be quite inefficient, performance-wise, if you had a fair number of expression triggers, and lots of setting of various variables very often.

Posted: Tue Sep 19, 2006 5:57 am

Oh yeah, *much* more efficient! In zMUD, everytime *any* variable changed (even if it was set to the same value), the button bar was updated, the status bar was updated, and it looped through all expression triggers and parsed them to figure out if anything needed to be fired. You can imagine how time consuming this could eventually get.

CMUD is super efficient. It knows the dependencies between various settings. So, a button is only updated when a variable that it depends upon changes. Same with a status bar, and same with expression triggers. Also, since things are compiled, testing the expression trigger doesn't require recompile/reparsing each time the variable changes. So if you use expression triggers, you will see huge benefits over zMUD.

Posted: Tue Sep 19, 2006 7:51 am

Wizard Joined: 14 Aug 2004 Posts: 1269

Zugg, I just thought it might be good to confirm if you have changed this in 1.06... I know you said above that it would be for 1.07, but it seemed like from you blog you may have changed it already for 1.06...

Wizard Joined: 25 Mar 2003 Posts: 1113 Location: USA

I had similar strange experiences with expression triggers in zMUD. I tried to use them for the logic in my combat scripts for Achaea, but they fired unpredictably and made the program run very slowly because of my dozens of variables constantly firing the triggers.

My hope is that expression triggers will be useful in building complex logic and keeping things somewhat centralized or generalized at the same time. This new CMUD compiler sounds like a great advancement for the MUD scripting world. Can't wait to really see what it can do when everything's all put together in the final version.

On a semi-related note (and hopefully not too much of a tangent), will the compiler handle nested custom functions better than zMUD? I had built up lots of custom functions for my complex logic, and I found that nesting too many of them too many levels deep brought zMUD to its knees.

Posted: Tue Sep 19, 2006 6:28 pm

Seb: Yes! Expression Triggers are in 1.06. You'll see them mentioned in the (long) version history. They should work just how you'd like them too now.

Larkin: There shouldn't be any problem with nested functions in CMUD, but give them a try and post a different thread with specific examples if something doesn't work right. I plan for more "traditional" functions in the future also.