R devel - Sep 2013 - Package installation and path.package

Dear R-Devels,

I am writing right now my own package that makes use of 'tempfile' and
there within with 'path.package'. When I install it, I get the error:
Error in path.package("mypackage") : none of the packages are loaded.
Here is the code, I use in my package:


".defaultDBPath"    <- function() 
{
    db.path <- tempfile(pattern     = "mmstructDB", 
                        tmpdir      =
file.path(path.package("mmstruct"),
                                                "data",
"databases"),
                        fileext     = ".db")
    return(db.path)
}

.mmstructBASE <- setClass("mmstructBASE",
                          		    representation("VIRTUAL",
                                                                    dbName     =
"character",
                                                                    dbTable    =
"character"),
                                            prototype(dbName      = character(),
                                                            dbTable     =
character()
							    )
)

.mmstructDB <- setClass("mmstructDB",                        
                        representation("VIRTUAL",
                                       conn = "SQLiteConnection"),
                        contains = c("mmstructBASE"),
                        prototype(conn  =
dbConnect(dbDriver("SQLite"), .defaultDBPath()))
)

I understand the error, but I would like to have a workaround. How can I give
the path to the package I am actually installing without getting this error?


Best

Simon

On Sep 9, 2013, at 4:22 AM, Simon Zehnder wrote:
> Dear R-Devels,
> 
> I am writing right now my own package that makes use of 'tempfile'
and there within with 'path.package'. When I install it, I get the
error: Error in path.package("mypackage") : none of the packages are
loaded. Here is the code, I use in my package:
> 
> 
> ".defaultDBPath"    <- function() 
> {
>    db.path <- tempfile(pattern     = "mmstructDB", 
>                        tmpdir      =
file.path(path.package("mmstruct"),
>                                                "data",
"databases"),
>                        fileext     = ".db")
>    return(db.path)
> }
> 
> .mmstructBASE <- setClass("mmstructBASE",
>                          		    representation("VIRTUAL",
>                                                                    dbName  
= "character",
>                                                                    dbTable 
= "character"),
>                                            prototype(dbName      =
character(),
>                                                            dbTable     =
character()
> 							    )
> )
> 
> .mmstructDB <- setClass("mmstructDB",                        
>                        representation("VIRTUAL",
>                                       conn = "SQLiteConnection"),
>                        contains = c("mmstructBASE"),
>                        prototype(conn  =
dbConnect(dbDriver("SQLite"), .defaultDBPath()))
> )
> 
> I understand the error, but I would like to have a workaround. How can I
give the path to the package I am actually installing without getting this
error?
> 
That path to your package is dynamic - in general it will not be know when
creating the lazy-load DB, so you really want to put that code in .onLoad()
where the path is known.

Cheers,
Simon

> 
> Best
> 
> Simon
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