[Solved][ZScript] Help with TryPickup()

[D2JK]

Could anyone help me with overriding the TryPickup() function? Vaecrius already tried to help me in the "How to ZScript" topic, but we couldn't make it work (Thanks Vaecrius, appreciate your effort).

Even this simple attempt gives me an error upon a pickup attempt: VM execution aborted: tried to read from address zero. In function parameter "self".

Code: Select all

Override bool TryPickup(actor Toucher)
  {
   return Super.TryPickup(Toucher);
  }

I'd be grateful if someone could show me the code for a working example with an extra if-check included in there(any sort of check would do fine).

[Fishytza]

Not sure why an if check is needed, but here's a working example.

Code: Select all

version "2.5"

Class MedMakesUJump : Stimpack replaces Stimpack
{
	//This stimpack will make you hop on successful pickup
	override bool TryPickup(in out Actor toucher)
	{
		bool result = Super.TryPickup(toucher);
		if( result ) toucher.Vel.Z = 20;
		return result;
	}
}

EDIT
The reason your example crashes is because "actor Toucher" must be "in out actor Toucher". That's what I did anyway.

[D2JK]

Neat, thank you very much! You're right; that small change would have been enough to let me proceed with this.

I also noticed that "out actor Toucher" seems to work as well, but then, I have no idea if omitting the "in" will have negative consequences at some point.

Lastly, since you wondered; I wanted to implement additional if - checks such as:

Code: Select all

if (toucher.GetPlayerInput(INPUT_BUTTONS)  &  BT_CROUCH)
 return Super.TryPickup(toucher);

[Graf Zahl]

I have no idea if omitting the "in" will have negative consequences at some point.

The 'in' is mostly syntactic sugar right now. In combination with an 'out' variable it would normally tell the function that the value being passed is readable but doing that properly was causing some logical issues in the compiler.

Normally when overriding a virtual function the entire signature (i.e. return value and all parameter types including qualifiers) need to be identical.

[Gutawer]

Lastly, since you wondered; I wanted to implement additional if - checks such as:

Code: Select all

if (toucher.GetPlayerInput(INPUT_BUTTONS)  &  BT_CROUCH)
 return Super.TryPickup(toucher);

It probably won't matter for booleans, but it's a better idea to use && for multiple checks in one statement - & is bitwise AND, and can cause unexpected behaviour if you are working with ints.

[D2JK]

Thanks, I'll keep that in mind.