Re: [Rd] Struggling with S3/S4 interface issues and External Pointers

From: Prof Brian Ripley <>
Date: Sat 22 Jan 2005 - 05:17:54 EST

On Fri, 21 Jan 2005, Jeffrey Horner wrote:

> I'm currently working on embedding R into the Apache2 webserver (with some
> positive results...), but I'm struggling to identify the best way to expose
> the apache data and functions to R.
> A couple of thoughts:
> In light of the recent discussion on "S3/S4 classes performance comparson",
> I'm leaning toward implementing the interface with S3 style classes. I
> appreciate anyones advice on this.

> I JUST found (after roughly 6 months of studying R) Luke Tierney's note on
> "Finalization and Weak References in R". From the developers page, this note
> is listed as a "preliminary mechanism", but I scoured CRAN and noticed
> packages like RODBC and XML are using it. Has this mechanism changed from
> "preliminary" to "production" yet? For storing pointers in R variables, I've

Yes, but the documentation has not. R itself uses the mechanism for DLLinfo.

The site is a mixture of old and new, but certainly worth perusing in the first month of studying R.

> been using integer vectors which is what RMySQL does but doesn't seem
> natural.

You asked elsewhere why RMySQL does not use it, but AFAIK it predates the mechanism. RODBC and XML have only used it recently.

Brian D. Ripley,        
Professor of Applied Statistics,
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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