[R] Scope and assignment: baffling

[Jeff Brown]

Hi,

The code below creates a value, x$a, which depending on how you access it
evaluates to its initial value, or to what it's been changed to.  The last
two lines should, I would have thought, evaluate to the same value, but they
don't.

f <- function () {
	x <- NULL;
	x$a <- 0;
	x$get.a <- function () {
		x$a;
	};
	x$increment.a <- function () {
		x$a <<- x$a + 5;
	};
	x
};
x <- f();
x$increment.a();
x$get.a();
x$a;

This can be repeated; each time you call x$increment.a(), the value
displayed by x$get.a() changes, but x$a continues to be zero.

Is that totally weird, or what?

Thanks,
Jeff
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