GameMaker function/method scope rules

scope rules.gml

/*
  Scope Rules:
  Caller == Whoever calls this method/function, is scoped to the caller. This is dependent on if there's an lvalue (lvalue.func()) or not. (for methods, the scope will be undefined).
  Instance == Regardless of whoever calls this method/function, it's scoped to the instance that declared it and not the caller. (Or if using method, whatever instance that was passed in the scope that's not "undefined")
*/

// Declared in a script 
// Scope == Caller, global (Will work no matter where you call it)
function myFunction() {
  
}

// Declared in a script 
// Scope == Caller, global (but only if used via global. and the script isn't the same name as the variable)
myFunction = function() {
  
}

// Declared in an object
// Scope == Instance (CE1: Will highlight as if it's global, it is not global)
// As of 2024.13, this actually breaks in hilarious ways that you should NEVER do this in an object.
function myFunction() {

}

// Declared in an Object
// Scope == Instance (Won't highlight)
myFunction = function() {

}

// Declared in an Object, with method
// Scope == Instance 
myFunction = method(self, OtherObject.myFunction);
// OR
myFunction = method(self, myGlobalFunction);
// OR
myFunction = method(self, function() {});

// Declared in an Object, with method and scope set to undefined
// Scope == Caller
myFunction = method(undefined, OtherObject.myFunction);
// OR
myFunction = method(undefined, myGlobalFunction);
// OR
myFunction = method(undefined, function() {});

// Declared in a constructor 
// Scope == Instance
function myConstructor() constructor {
  myFunction = function() {

  }
}

// Declared in a constructor, but with static
// Scope == Caller
function myConstructor() constructor {
  static myFunction = function() {

  }
}

// Declared in an object, but assigned to another object
// Scope == Insstance (declared by objectA)

// objectA create event
objectB.func = function() {
  return object_get_name(object_index);
}

show_message(objectB.func()); // Prints out "objectA"