[R] Function arguments and copying objects

[Prof Brian Ripley]

R-devel is the appropriate place for C programming questions: please DO 
read the posting guide.

You need to check the NAMED flag and call duplicated as necessary.
There are many examples in src/main/*.c.

On Tue, 10 May 2005, Giovanni Petris wrote:

>
> I have a function that, via .Call, modifies its argument, so I first
> create a backup copy of the object I want to pass, make a copy of it,
> and pass the copy to the function. However, my function also modifies
> the backup copy. I guess this has to do with R not duplicating objects
> until they are modified. Where can I read more about that? And/or how
> can I solve my problem, i.e. save a copy of the argument?
>
> Here is an example of what I mean:
>
>> mod.back$m0 <- rnorm(2)
>> mod.back
> $m0
> [1] -0.03431583 -1.66513535
>
> ...
>
>> mod <- mod.back
>> dlmLLsvd(ip,mod)
>> mod.back
> $m0
> [1] 3.360737 3.266844
>
> ...
>
>
> Thanks in advance,
> Giovanni
>
> -- 
>
> __________________________________________________
> [                                                  ]
> [ Giovanni Petris                 GPetris at uark.edu ]
> [ Department of Mathematical Sciences              ]
> [ University of Arkansas - Fayetteville, AR 72701  ]
> [ Ph: (479) 575-6324, 575-8630 (fax)               ]
> [ http://definetti.uark.edu/~gpetris/              ]
> [__________________________________________________]
>
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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)
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