A number of packages do this. See e.g. 'sm' and its function
sm.options() for one implementation.
On Wed, 3 Feb 2010, Duncan Murdoch wrote:
On 03/02/2010 8:07 AM, Chris Brien wrote:
Dear all,
I am developing a package foo that has a namespace. I would like to be able
to provide an option, say opt, that
1) is set to a default value when the package is loaded
2) can be set to a different value by the package user
3) is used by functions within the package
How can I achieve this?
Do you want this option to persist to the next session if a user saves the
workspace? If so, then it should be stored in a variable in the global
environment. You can use assign(".FooOptions", value, envir=globalenv()) to
set it, and get(".FooOptions", envir=globalenv())
to read it.
The obvious problem with this is that the user might already have a
.FooOptions variable defined, and your code would stomp on it. An
alternative is to store the variable into the namespace. You need to unlock
it to change it. See tools:::startDynamicHelp for code that does this for
the variable httpdPort.
Duncan Murdoch
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Brian D. Ripley, rip...@stats.ox.ac.uk
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