'and' function?

[mitsuki]

I want it to be so that if
user clicks on object
AND
variable1>0
then
create object blah blah blah

So I did that, with just inserting the 2nd condition, with no OR or anything in between, and its treating it like there IS an OR in between.
So how do I make it so that BOTH conditions must be fulfilled for it to activate?

[Tomssuli]

Did you addd the 2nd condition to the same event by pressing the first events number with right mouse and select "add a new condition" or did you make a new event altogether? ...You should add to the same event so it should work.

[nivram]

nivram overlaps duffus block
+Age is > 57
+Only one action when event loops
>Create a new nivram

When both coditions are true, a new nivram is created.

Marv

[Alonso]

Those two conditions should be under the same event. It naturally assumes an "and" operation.

I'd like to see a "+ event #xx is true" condition, though.

[Pixelthief]

when you have multiple conditions in the event editor, it is treated by default as if they have "AND" between them. The "OR" requires you to insert it between them.


In MMF2, it is not exactly parallel with how it works in other languages. To understand it, you need to grasp how the "Object Selection List" or "Object Scope" works in MMF. Basically, at the start of every line of code, the object scope is set to all objects. The list will include a pointer to every single object in the game.

When you run a condition, it will take one of two actions:
A) The condition will resolve "TRUE" and unscope all copies of the object that did not resolve TRUE on a per-object basis
B) The condition will resolve "FALSE"

If *any* condition resolves "FALSE" the actions in the event will not execute (MMF does not use "short circuit" or "lazy" evaluation and will eval all conditions even if a previous one was false... but it might not read it at all if it depended on an "immediate" like an "On Loop" condition, which tells MMF2 *when* to parse it)


This object scope list will keep being modified as the list goes down. So if you start off with 10 objects, your first condition might specify 6 of them- the other 4 objects will be discarded. Your second condition might specify 2 of these 6- the other 4 will be discarded. Your third condition might specify none of these 2- that condition would resolve "FALSE" and no actions would be taken.



By having this object list manipulation, MMF2's conditions simulate an "AND" inbetween each condition in an *in-order* basis. Having nonrelated conditions like
"Global Value A > 0"
and
"Repeat while Space Bar is pressed"

will act just like any other language- it will only execute its actions if both are true, and won't do anything if either are false. However, conditions which act upon the same space of objects might sometimes care about order:


"Object Value A > 0"
"Pick an Object at Random"

In that order, it picks a random object out of the pool of objects with value A > 0. In the other order, it picks a random object out of all objects, and then checks if its value A > 0- if it isn't, the line will not resolve.





Oh yeah, and remember: if even a single condition resolves "FALSE", the line will not execute, whereas for each condition, if even a single object resolves "TRUE", the condition will resolve "TRUE".

[Dynasoft]

If *any* condition resolves "FALSE" the actions in the event will not execute (MMF does not use "short circuit" or "lazy" evaluation and will eval all conditions even if a previous one was false...)

This is incorrect. MMF will stop testing conditions in an event if one is false for all applicable objects.

On the other hand, with an "OR" in the event, MMF may evaluate both sides even if the first side was true, in order to get an accurate object selection list.

EDIT: In other words, MMF short-circuit evaluates "and" conditions, but not "or".

[Pixelthief]

If *any* condition resolves "FALSE" the actions in the event will not execute (MMF does not use "short circuit" or "lazy" evaluation and will eval all conditions even if a previous one was false...)

This is incorrect. MMF will stop testing conditions in an event if one is false for all applicable objects.

On the other hand, with an "OR" in the event, MMF may evaluate both sides even if the first side was true, in order to get an accurate object selection list.

EDIT: In other words, MMF short-circuit evaluates "and" conditions, but not "or".

Hrmm wow ok I always thought it was otherwise, but I just tested it with some complex fast looping and indeed you're right, it does use short circuit evaluation. Nevermind that part of my post then.

[UrbanMonk]

even I knew that pixeltheif! Geez

[Corentin]

That's why you should put the most restrictive and less time-consuming conditions on top, to avoid making more tests than needed