Definition of virtual, const and vararg function classifications in the docs

[wyattbiker]

In the API docs, e.g. http://docs.godotengine.org/en/3.0/classes/class_node.html you see functions classified as virtual, const and vararg. I am trying to understand what that means with respect to the functions.

So I am guessing virtual classification is similar to abstract, and must be defined in your code (E.g. callbacks). But const or vararg classification I am not so sure. What does this classification mean?

Examples.

void    _ready ( ) virtual
Node    get_child ( int idx ) const
Variant rpc ( String method ) vararg

[LikeLakers2]

From what I can tell:

• virtual means that's a function for a event. The function is supposed to be defined in your own code, with your own code. For example, if you want some code to run when the node is ready, you would define _ready() with that code; If you want to run code whenever there is input from a controller, mouse, or keyboard, you would define _input(event); and so on. If not defined, these typically do nothing.

• const seems to mean that the function, given the same arguments and same context every time, will always return the same value. For example, get_child(5) will always return the child at index 5, assuming that no child nodes are ever removed. get_parent() will always return the same parent, assuming the node hasn't been moved to another parent in the scene tree. And so on. (I may be wrong on this, but this is what I always understood about const)

• vararg means that the method can accept any number of arguments (including no arguments) after the ones explicitly shown. For example, print() is a vararg function, which means you can pass more than one argument to it and it will react accordingly. In the case of print(), it will just print the arguments in order, on the same line. print('a', 'c', 'b') will print acb.

[vnen]

const actually means that the function has no side-effect, i.e. it won't change any property of the object when called.

[wyattbiker]

Thanks for the explanations which make sense. It does need to be explained in the docs (unless it is described some place and I did not find it) because I know i asked elsewhere and I had differing answers.