[R-pkg-devel] Recommendations about adding options to a package in order to change default values of some functions on-the-fly

[Alexandre Courtiol]

Dear Samuel,

Many may object (for good reasons) that adding options would clash with
functional paradigm, but it is possible.
I don't know about the least worse practice but as far as I would do it,
you could:

1. directly write and then read elements in the (hidden) list .Options that
is present in the global environment:
options(test = "blabla") ## add element in .Options
.Options$test ## read element (for use in your own function)

2. you could also create your own alternative to options(), as ex:
https://github.com/courtiol/IsoriX/blob/master/IsoriX/R/options.R
Option 2 has the benefits of not risking conflict with existing names in
.Options and it would thus also not mess up the way other packages may work.
Option 1 uses what is already in place.

I hope this help,
Best

Alex

On Thu, 6 Sep 2018 at 17:18, Samuel <samuel.granjeaud using inserm.fr> wrote:

> Hi,
>
> I would like to change the default value of some arguments of some
> functions in a package of mine. I don't want to change explicitly the
> calls in the many scripts that have been written. For example, I would
> to change the delimiter in all write.mytable() without changing any
> calls it and without changing the default value currently assigned to
> that delimiter in the declaration of this function. What I would like is
> to add a command at the beginning of the scripts that says "since now,
> the delimiter is ;".
>
> I am thinking about setting global options that those functions will
> read and use to overwrite the default values. Of course the
> write.mytable function has to be modify to exploit these settings, but
> none of the scripts. I think about something similar to the par() and
> options() functions.
>
> I noticed the settings package, but I would like to know if there is a
> simple and recommended solution without adding any dependency.
>
> Hope my question is clear.
>
> Thanks for any advice,
> Samuel
>
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-- 
Alexandre Courtiol

http://sites.google.com/site/alexandrecourtiol/home

*"Science is the belief in the ignorance of experts"*, R. Feynman

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