Replace PROTECT with Shield<>

[eddelbuettel]

This addresses the concern by Tomas Kalibera (see here) and updates ChangeLog and NEWS.

[armstrtw]

I don't think we need this.

Do you think shield is better?

His check code doesn't really work for c++.

[eddelbuettel]

Yes I do think Rcpp::Shield<> is better. It is also super-simple. No loss here.

But I agree that his check gets tripped up. He also sent me a false positive for the (old !!) RcppClassic where things happen correctly in the destructor but he didn't see that.

[eddelbuettel]

The bigger story is of course that we could just as well

        ans = Rcpp::LogicalVector(n, NA_LOGICAL);

instead of

        ans = Rcpp::Shield<SEXP>(Rf_allocVector(LGLSXP,n));
        std::fill(LOGICAL(ans),LOGICAL(ans)+n,NA_LOGICAL);

[eddelbuettel]

Ie

R> library(Rcpp)
R> cppFunction("LogicalVector makeOne(int n) { return LogicalVector(n, NA_LOGICAL); }")
R> makeOne(3)
[1] NA NA NA
R> class(makeOne(3))
[1] "logical"
R> 

[eddelbuettel]

If you have a moment over the weekend I would appreciate it if you could glance at this.

[armstrtw]

Wil do. Just straight from work to dinner.

[armstrtw]

I'm looking at the source for shield.

It doesn't do out of order destruction. In this case, it doesn't really matter.

Why not use UNPROTECT_PTR ?

Anyway, his check is just bogus, so there's not really a need to make this change. but if you want to make the code more 'Rcppish' I'm ok with that.