#### is source(*, local=TRUE)d	 from /u/sfs/R/Rprofile --
#### at each regular R startup at SfS

libPIns <- function(nlib, beforeLib, msgTxt, doWarn = TRUE,
		    MSG = if(interactive()) message else function(...) invisible())
{
    ## Purpose: Insert a directory into .libPaths() *before* another one
    ## ----------------------------------------------------------------
    ## Arguments: nlib:	 The library directory to insert
    ##	     beforeLib:	 (grep-pattern of an) entry in current .libPaths()
    ##		msgTxt:	 optional message text about the insertion
    ## ----------------------------------------------------------------
    ## Author: Martin Maechler, 2006

    lp <- .libPaths()
    if(file.exists(nlib)) {
	if(!any(nlib == lp)) {
	    if(length({fl <- list.files(nlib); fl[fl != "R.css"]})) {
		## only if the library contains any packages :
		if(!missing(msgTxt) && is.character(msgTxt))
		    MSG("extending .libPaths() ", msgTxt," ...")
		ni <- length(iL <- grep(paste(beforeLib,"$",sep=''), lp))
		if(ni != 1) {
		    warning(".libPaths() contains ",
			    if(ni>1) "more" else "no",
			    " entries matching ",sQuote(beforeLib))
		    iL <- if(ni > 1) iL[1] else length(lp)
		    MSG("Inserting before position ", iL," ..")
		}
		ii <- 1:length(lp)
		.libPaths(c(lp[ii < iL], nlib, lp[ii >= iL]))
	    } else if(doWarn) {
		MSG("library ", sQuote(nlib),
		    " with no packages *not* added to lib path")
	    }
	}
    } else if(doWarn) warning(nlib, " is not an existing directory")
}