On Sat, Jun 25, 2011 at 9:21 PM, Prof. John C Nash <nas...@uottawa.ca> wrote:
> In building a function for a package, I'd like to set the defaults in a
> control list,
>
> e.g.,
>
> makeg<-function(parameters, eps = 1.0e-7, control=list(showwork=TRUE,
> rubbish=1.0e+101)){
>
> etc.
> }
>
> This does not provide showwork or rubbish within the function if control() is
> not fully
> specified. Copying others, I've previously set the control defaults within
> the function
> then matched names, and that certainly works. I'm happy to keep using that
> approach, but
> would like to have a pointer to good practice for doing this (I'm prepared to
> write or
> help write a short tutorial if none exists).
>
> I can understand that trying to do the default replacement at a second or
> greater level
> could give problems. A search through the language definition and some
> googling didn't
> show up any obvious warning about this, but I'm sure there are some comments
> somewhere.
> Can anyone suggest some URLs?
>
> One gets used to the nicety of being able to specify defaults and forgets
> that even R has
> some limits.
>
See ?modifyList
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