[Rcpp-devel] namespace trick required

[Romain Francois]

Le 25/11/10 11:17, Romain Francois a écrit :
> Hello,
>
> With formals<- I added into Rcpp yesterday, I have updated the parser
> package as such:
>
>
>
> NAMESPACE <- environment()
> MODULE <- Module( "parser_module" )
>
> nlines <- function( file ) NULL
> count.chars <- function( file, encoding = "unknown" ) NULL
>
> .onLoad <- function( libname, pkgname ){
> unlockBinding( "nlines" , NAMESPACE )
> unlockBinding( "count.chars" , NAMESPACE )
>
> nlines <- MODULE$nlines
> formals( nlines ) <- alist( file = )
> assign( "nlines", nlines, NAMESPACE )
>
> count.chars <- MODULE$count.chars
> formals( count.chars ) <- alist( file = , encoding = "unknown" )
> assign( "count.chars", count.chars, NAMESPACE )
>
> lockBinding( "nlines", NAMESPACE )
> lockBinding( "count.chars", NAMESPACE )
> }
>
>
> This is somewhat annoying that we have to first create dummies for
> "nlines" and "count.chars", and then hijack them on the .onLoad.
>
> Can anyone think of another way ?

Ah. This is what happens when you send a message too early. We actually 
don't need the dummies and can do:

NAMESPACE <- environment()
MODULE <- Module( "parser_module" )

.onLoad <- function( libname, pkgname ){
	
	nlines <- MODULE$nlines
	formals( nlines ) <- alist( file = )
	assign( "nlines", nlines, NAMESPACE )
	
	count.chars <- MODULE$count.chars
	formals( count.chars ) <- alist( file = , encoding = "unknown" )
	assign( "count.chars", count.chars, NAMESPACE )
	
	lockBinding( "nlines", NAMESPACE )
	lockBinding( "count.chars", NAMESPACE )
}

I'm thinking about :
- deal with the formals internally
- add an R function that would dump functions and classes from a module 
into an environment or a namespace.

Romain


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Romain Francois
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