Enter/Exit Turfs

ID:2124186
 
Jul 30 2016, 2:08 pm
(See the best response by Ter13.)
Code:

    FloorTutorial
        name=""
        icon='Turfs.dmi'
        icon_state="tile2"
        Enter(mob/M)
            ..()
            if(ismob(M))
                //Trap/Spawning Procs here
                return 1
            else if(isobj(M))
                return 1
            else ..()
        Exit(mob/M)
            ..()
            if(ismob(M))
                return 1
            else if(isobj(M))
                return 1
            else ..()


Problem description: I'm simply trying to make so certain tiles spawn monsters or deal damage but mobs and objs on it have no density? or rather I'm Walking over things that should.

Jul 30 2016, 2:15 pm
I would say first remove ..() from the beginning of both enter/exit.

Then I can't 100% tell what you are doing here but I would say keep in mind that return 1 allows you to enter, and return 0 prevents you from entering.

And finally I would say try using else return ..() instead, which returns the default value of Enter/Exit.
Jul 30 2016, 2:36 pm
Best response
Clusterfack is on point here. Enter() and Exit() MUST return a value. If it fails to return a true value, entry/exit will fail.

Calling ..() simply invokes the supercall (previously defined behavior), so you RARELY will ever need more than one in the same execution path.

. = ..() at the end of an execution path or return ..() to force execution to end is the main problem.

Also, I'd advise against checking isobj(), because atom/movable derives only into two types: /mob and /obj. If M is not a mob, it will be an object ALWAYS. Even if you forcibly define something as /atom/movable, the compiler forces it to be a subtype of /obj.

Lastly, you shouldn't be using Enter() in the first place. Enter() determines whether something can enter a tile, not whether something has entered the tile.

Instead, here's what I'd recommend:

turf/trapped
    proc
        Triggered(mob/M)
        Untriggered(mob/M)

    //when the tile is stepped into
    Entered(atom/movable/o)
        ..() //only if necessary
        if(ismob(o))
            Triggered(o)
        /*efficiency freak version:
        ismob(o)&&Triggered(o)
        */

    Exited(atom/movable/o)
        ..() //only if necessary
        if(ismob(o))
            Untriggered(o)
        /*Efficiency freak version:
        ismob(o)&&Untriggered(o)
        */


Now using this base behavior, you can perform polymorphic overrides to create new traps:

turf/trapped/spikes
    Triggered(mob/M)
        M.TakeDamage(25)
turf/trapped/pressureplate
    var/tmp
        obj/link
    Triggered(mob/M)
        link&&link:Signal(src,M)
    Untriggered(mob/M)
        link&&link:Unsignal(src,M)


TL;DR: Enter() is a question. Entered() is the response. Use Entered() in the case where you want something to happen when something steps into a tile.