[Rd] Top-level code in packages

[Prof Brian Ripley]

On Sat, 3 Jul 2004, Frank E Harrell Jr wrote:

[...]

> I use that sort of construct a lot, except that tools::: can't be used 
> in general for backwards compatibility and for compatibility with 
> S-Plus.  But often I use the following construct and would like to keep 
> doing so, especially when defining functions for compatibility when the 
> function only needs defining for a subset of the supported systems:
> 
> if(.R. || .SV4.) {  # variables defined in Hmisc or Design package
>   foo <- function( . . . ) {
>   }
>   NULL   # prevents printing a result in S-Plus
> }

That's fine, as its effect is a top-level assignment and nothing else 
useful (the NULL will be pointless, but who cares).


-- 
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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