[Rcpp-devel] Vector<>::create

[Romain Francois]

Le 19/03/10 15:03, Dirk Eddelbuettel a écrit :
>
>
> On 19 March 2010 at 14:01, Romain Francois wrote:
> | I've commited Vector<>::create methods to support creation of any kind
> | of vectors with named or unnamed objects. examples:
> |
> | // creating an unamed integer vector
> | IntegerVector::create( 10, 20 ) ;
> |
> | // creating a named character vector
> | CharacterVector::create( _["foo"] = "bar", _["bar"] = "foo" ) ;
> |
> | // creating a named list
> | List::create( _["foo"] = 10, _["bar"] = true ) ;
> |
> | The syntax :
> |
> | _[.] = .
> |
> | can be replaced by this for people who don't like _ :
> |
> | Argument( . ) = .
> |
> | so for example :
> |
> | List::create( Argument("foo") = 10, Argument("bar") = true ) ;
>
> Really nice work!

It was quite challenging ... but where is the fun otherwise ?

> | I could not use Named as it is now because it wraps the object too early
> | and so would only work for lists (which contains SEXP) and would not
> | work for e.g. integer vectors.
> |
> | Here the rhs of Argument::operator= is kept as a reference until it is
> | effectively stored in the object, so Argument::operator= makes an object
> | of the template class traits::named_object which create knows how to
> | deal with, but the key is that named_object does not wrap but only
> | contains reference.
> |
> | The new question is : should "Argument" be called something else ?
> | Should I rework all others clients of Named so that they use Argument
> | instead (in that case I would then call it Named).
>
> Tricky one. We'd be altering a published interfaces which is bad, but then
> the paint is barely on these interfaces. I guess this can be argued either
> way.  What do you think?   What do other lurkers thing?

about this, instead of being a class, we make Named a templated 
function. With this I think we could preserve both syntax:

Named( "x" ) = 10 ;
Named( "x", 10 ) ;

I don't think anyone cares that Named is a class, as it is only 
typically used inside other constructs for its side effect.

I think this way we would just alter what Named is but keep what it is 
used for intact.

Romain

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Romain Francois
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