How do i make newly spawned monsters execute a specific script?

Give a specific tag to the newly spawned monsters via your spawn function, then use SetThingSpecial to assign an action and arguments to monsters with this tag.

@scifista42

So ive set the monsters all an id off 999 when they spawn in.

This is the script that i am using to tie them to script 3.

Quote

script 8 (void)

{
    SetThingSpecial(999,ACS_ExecuteAlways,3,1);
    }
 

This is script 3 - the script that gives the player xp upon a monster kill

Quote

script 3 (void)

{
    playerXp = playerXp +5;
}
 

Yet upon killing them in game the script is not executing and not providing XP. 

Have i done something wrong?

You need to call the script 8 after the monsters have spawned.

If even that isn't working, post the map.

Show the code or physical setup that spawns the monsters and that calls script 8 afterwards. Also, the "map" argument for ACS_ExecuteAlways should better be 0.

Rule of thumb: delay 1 tic before assigning specials to things that need to be spawned in via ACS. Like this:

Thing_SpawnFacing(stuff);
Delay(1);
SetThingSpecial(stuff);

Delay is not necessary, spawning happens immediately as the spawn function is called, and therefore the spawned objects are guaranteed to exist and be fully prepared to be used when the script proceeds to call the next function.

Delay would be necessary if it was somehow ambiguous or unpredictable whether the spawn function would be called before or after the other function, while also certain that they would both be called in the same tic (if the delay wasn't applied). But if they're written in sequence and the spawn function is the first one, it's unambiguously called first.

I've got it to work by doing what @Nevander suggested and adding a delay in the same script that summons the monsters before the SetThingSpecial. This actually seems a bit more convenient to code as i don't have to create an entirely different script to assign the monsters to give Xp. Plus the code is near the lines that summon the monsters in question which is nice for organisation. Thanks everybody for the advice :)

Edit: Ive just realised i can get it to work without the delay :)