Make a physical copy of a plot object
This functionality does not run in MATLAB.
Plot objects usually have a reference effect. plot::copy creates copies which are independent of the original.
Objects created from inside the plot library have a reference effect: If you make another reference to some object, say by calling o2 := o1; and then change an attribute of o2, e.g., setting o2::Visible := FALSE, this change will also effect the object referred to by o1, since they actually refer to the same object. To create an actual copy of an object instead, use o2 := plot::copy(o1);.
The function plot::modify is a variant of plot::copy. It allows setting new values of attributes in the same call, as in o2 := plot::modify(o1, Visible = FALSE);.
The following call does not create two points, but rather one which we can access by two names:
A := plot::Point2d(0, 0): B := A:
This surfaces as soon as we try to modify `one of the points':
B::Position := [1, 1]: A
Instead, we can use plot::modify to achieve the desired effect:
B := plot::modify(A, Position = [2, 2]): A, B