[Rd] reference class internals

Hadley Wickham h.wickham at gmail.com
Thu Jan 9 23:43:44 CET 2014

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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