Re: [Rd] Getting param names of primitives

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Wed, 11 Jul 2007 13:17:16 +0100 (BST)

My problem is that if we make formals() work on primitives, people will expect

formals(log) <- value

to work, and it cannot.

On Wed, 11 Jul 2007, Martin Maechler wrote:

>>>>>> "BDR" == Prof Brian Ripley <ripley@stats.ox.ac.uk>
>>>>>> on Wed, 11 Jul 2007 05:48:56 +0100 (BST) writes:
>
> >> formals(args(log))
> BDR> $x
>
>
> BDR> $base
> BDR> exp(1)
>
> BDR> gives what formals(log) used to.
>
> (I knew). I've been asking myself several times now,
> if we should not make
> formals() do this automatically.
> I know that the change might break some code
> which has used things like
>
> if(is.null(formals(fun))) {
>
> ## treat fun as a primitive function
>
> }
>
> but I think R has provided is.primitive(.)
> long enough now so that
> we could consider the change.
>
> Martin
>
>
> BDR> On Wed, 11 Jul 2007, miguel manese wrote:
>
> >> Hi,
> >>
> >> In the latest R this does not work anymore
> >>
> >> args <- formals(log)
> >>
> >> because log is primitive. Is there any other way to get the argument
> >> list? I just need the name of the parameter to display some error
> >> message about it. I have looked at args() but I can't find anything to
> >> extract the argument names from it.
> >>
> >> Thanks,
> >> M. Manese
>
> BDR> --
> BDR> Brian D. Ripley, ripley_at_stats.ox.ac.uk
> BDR> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
> BDR> University of Oxford, Tel: +44 1865 272861 (self)
> BDR> 1 South Parks Road, +44 1865 272866 (PA)
> BDR> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
> BDR> ______________________________________________
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>
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-- 
Brian D. Ripley,                  ripley_at_stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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