Function To Change Value

[killerogue]

I feel as if I'm probably missing something asking this, but as anyone here ever made a function to set a new value to an old one?

I was trying to do something like:

NPC 1

PHP Code:

function onCreated() {
  core = this;
}

function setValue(oldVal, newVal)
(@ oldVal) = (@ newVal); 


NPC 2

PHP Code:

function onCreated() {
  this.on = true;
  this.on = core.setValue(this.on, (this.on = !this.on));
  echo(this.on);
} 


Echoes nothing. >_>