[Rd] reference class internals
matloff at cs.ucdavis.edu
Fri Jan 10 00:20:17 CET 2014
Bottom line: Really no different from the case of ordinary vectors that
are not in reference classes, right? In other words, not true
On Thu, Jan 09, 2014 at 04:43:44PM -0600, Hadley Wickham wrote:
> It's a bit of a simplification, reference classes are wrappers around
> environments. So if modifying a value in an environment would create
> a copy, then modifying the same value in a reference class will also
> create a copy.
> The situation with modifying a vector is a bit complicated as it will
> sometimes be modified in place and sometimes be duplicated and
> modified (depending on whether its NAMED attribute is 1 or 2, and
> exactly how you're modifying it).
> On Thu, Jan 9, 2014 at 4:33 PM, Norm Matloff <matloff at cs.ucdavis.edu> wrote:
> > I have a question about reference classes, which someone here
> > undoubtedly can answer immediately, saving me hours of wading through
> > indecipherable internal code. :-) Thanks in advance.
> > Reference class data is mutable, fine, but in what sense? Is it really
> > physical, or is it just a view given to the programmer?
> > If for instance I have vector as a field in a reference class, and I
> > change one element of the vector, is it really true that the change is
> > guaranteed to be made in-place, no copying, no memory reallocation etc?
> > Norm
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