[Rcpp-devel] feature proposal: ListOf

[Kevin Ushey]

Other thing worth considering for implementation: how might it fit in
with Rcpp Attributes? It would be very nice if we could define a
function like

// [[Rcpp::export]]
ListOf<IntegerVector> fun( ListOf<IntegerVector> x ) {
   ...
}

and have the wrapper function automatically generated as we're used
to. Ideally, ListOf would have most of the non-ctor methods from List
as well.

Should the constructor do validation on the contents (ensure all
elements in the ListOf object have the template type)? Or could that
be part of a separate method (e.g. validate)?

That said, this would be a lot of work and I understand if it's not a
priority. I'd like to contribute to the implementation but my C++
programming chops aren't up to par yet... unit tests and examples, I
can gladly contribute though.

Let me know if you get a chance to revisit this later.

-Kevin

On Fri, Oct 25, 2013 at 12:00 PM, Romain Francois
<romain at r-enthusiasts.com> wrote:
> Cool. I've got lots on my plate right now, so this is not a priority.
> Did you have a chance to look at the (simplistic) implementation of ListOf
> in dplyr:
> https://github.com/hadley/dplyr/blob/master/inst/include/tools/ListOf.h
>
> The indexing operator should be proxified so that we could handle
> assignments, i.e.:
>
> NumericVector z ;
> ListOf<NumericVector> x( xxx );
> x[0] = z ;
>
> At the moment it only has read access because that's all I needed for now in
> dplyr.
>
> So maybe if we wanted something more generic in Rcpp, this should be
> designed a bit more.
>
> Romain
>
> Le 25/10/2013 20:40, Kevin Ushey a écrit :
>
>> Hi Romain, Dirk,
>>
>> I'd be willing to contribute an Rcpp Gallery post and some tests if
>> this were added to Rcpp; I think it would be quite useful.
>>
>> -Kevin
>>
>> On Wed, Oct 23, 2013 at 6:31 AM, Dirk Eddelbuettel <edd at debian.org> wrote:
>>>
>>>
>>> On 23 October 2013 at 14:31, Romain Francois wrote:
>>> | Le 23/10/2013 13:47, Dirk Eddelbuettel a écrit :
>>> | > As always, preferably with a usage example (Rcpp Gallery post?
>>> Section in a (new)
>>> | > vigntte?) and tests so that people have some info on how to use it.
>>> |
>>> | That means it will take me more time than what I wanted to commit to
>>> | this. I'll come back to it later then.
>>>
>>> Up to you.  FWIW your previous commits are still undocumented in NEWS.Rd.
>>>
>>> Dirk
>>>
>>> --
>>> Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
>
>
>
> --
> Romain Francois
> Professional R Enthusiast
> +33(0) 6 28 91 30 30
>