[R] R package: Where to put code to Run Once Only?

[Martin Morgan]

Rolf Turner <r.turner at auckland.ac.nz> writes:

> On 7/04/2009, at 3:34 PM, Ken-JP wrote:
>
> 	<snip>
>
>> Using NAMESPACE, I was able to hide my globals behind a  "." (eg
>> .myGlobal
>> <<- 72) and use exportPattern("^[^\\.]*") to prevent users from
>> seeing my
>> globals, yet I was able to access their values inside my package.
>
> 	<snip>
>
> 	WHY do you want to ``prevent users from seeing [your] globals''?
>
> 	The whole point of R (well, maybe not the whole point, but a major
> 	point) is to be adaptable.  If something doesn't work the way a user
> 	wants, then the user can change things.  When the inner workings
> 	are hidden so deeply that the user can't see what to change, this
> 	becomes effectively impossible, and the user might as well go and
> 	use SAS.
>
> 	I exaggerate but slightly.
>
> 	Nevertheless, this syndrome of hiding things and making them
> 	effectively
> 	inaccessible --- which seems to have become an obsession with some

ls(getNamespace("<pkg>"), all=TRUE)

gets all the symbol names.

<pkg>:::symbol

gets non-exported values. What does the 'user' get in return? A
cleaner interface to the important functionality of the package,
faster symbol lookup, reduced opportunities for symbol masking between
packages. And with use of Imports:, unambiguous symbol look-up within
the package and shorter symbol search path.

Martin

> 	of the
> 	R community, particularly many of the senior members --- bugs the
> 	living
> 	Drambuie out of me.
>
> 		cheers,
>
> 			Rolf Turner
>
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-- 
Martin Morgan
Computational Biology / Fred Hutchinson Cancer Research Center
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