Added constructor to instantiate newDatetimeVector from VectorBase.

[dcdillon]

This fixes the issue where

#include <Rcpp.h>


// [[Rcpp::export]]
Rcpp::newDatetimeVector test(Rcpp::newDatetimeVector v) {
    Rcpp::newDatetimeVector x = v + 2.;
        return x;
}

failed to compile.

It, however, is likely that other issues will crop up at some point due to other missing constructors (since Vector has so many and newDatetimeVector has so few). I'd like opinions on whether the rest of the Vector constructors should be ported to newDatetimeVector at this time, or if we should just wait and see what breaks and port them one at a time.

The same applies to operator=, as there don't exist any operator= functions that return newDateTimeVector &.

[eddelbuettel]

Thank you. We probably want to
a) toss operator= in while we're at it, and
b) do the same for newDatevector.
If nobody gets to it I can do it while riding the train downstate next Thursday.

[dcdillon]

I'll add that stuff tonight.

[eddelbuettel]

Maybe get newDatetimeVector right first, and then add things to newDatevector ?

[dcdillon]

Seems fair. The one thing that bothers me is that it's likely that some weird issues will bite us later on with missing ctors and assignments, but I also don't want to create a huge PR of largely untested code.

[eddelbuettel]

What is your timeline for adding operator=()? Shall I merge now and we revisit extension later?

[dcdillon]

Sorry. I ran into a weird issue on my machine and was getting check fails that I didn't understand and just haven't gotten back to it. Feel free to merge this and I'll get to the rest when I can

[eddelbuettel]

Yes, let's do that.