setting global options for a package

On May 10, 2012, at 9:59 AM, Michael Friendly wrote:

This may be elementary, but I can't find an answer: How can I set up global options for
some specific arguments to functions in a package which can be easily changed by the user?

This question relates to the selection of colors used in functions in several packages (heplots,
genridge), where I want to provide reasonable default values for plots, but allow users to
change those defaults globally for all plots produced with my functions.

One solution is to use palette() for the default, as in

foo <- function(x, col=palette(), ...)  {}
but the standard palette is not appropriate for my use, and I'd rather not hijack more typical uses

Another is to use an explicit list of colors for default, as in

bar <- function(x, col=c('red', 'blue', 'brown', 'darkgreen', ...), ...)  {}
but this must be overridden each time by someone to wants to change the defaults.

options() seems like the way to go, but I'm not sure how to implement this.  If I use
a .onLoad function to set some options, will these be created in the global environment?
If not, how to make them so?

.onLoad <- function() {
 options(heplot.colors =
 c("red", "blue", "black", "darkgreen", "darkcyan","magenta", "brown","darkgray"))

You certainly don't want to do that - it would override user's setting and thus defeat the whole purpose of options.

}

My function could then use

foo <- function(x, getOption("heplot.colors"), ...)  {}

You can always do that:

foo <- function(x, heplot.colors = getOption("heplot.colors"), ...)  {
  if (is.null(heplot.colors)) heplot.colors <- c("red", "blue", "black", "darkgreen", "darkcyan","magenta", "brown","darkgray")

Cheers,
Simon

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
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