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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