Re: [Rd] Top-level code in packages

Prof Brian Ripley wrote:
> On Fri, 2 Jul 2004, Frank E Harrell Jr wrote:
>
>

>>Brian Ripley stated that in the future it will not be a good idea to 
>>have top-level code in R packages other than assignments.  There is one 
>>important exception, though it leads instantly to an assignment.  To 
>>maintain compatibility across multiple platforms (R, S-Plus, and more 
>>than one version of each, Windows, Linux, etc.) I frequently use if( ) 
>>statements to conditionally define functions depending on the operating 
>>system and the version of R or S-Plus in effect.

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 }

>
> BTW, if you want to test the OS you can't do it with .Platform$OS.type and
> allow cross-building, hence the test illustrated.
>

Thanks Brian,

Frank

-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University

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