[Rd] Saving Rcpp Objects for Future Use

[Dirk Eddelbuettel]

Hola,

On 9 September 2011 at 16:07, Michael King wrote:
| Hello,
| 
| I have recently been doing some research regarding how to successfully save
| and load Rcpp Objects ( objects from modules ) for future use, but with
| little success. For example, to use the example package (from package
| skeleton) in Rcpp:
| 
| >library(Rcpp)
| >Rcpp.package.skeleton("rdevelhelp", module=TRUE)
| ...
| > q()
| // install rdevelhelp using R CMD INSTALL
| // load new R Session
| 
| >library(rdevelhelp)
| >x <- new(World)
| >x$set("help me")
| >x$greet()
| "help me"
| >save(x, "x.RData")
| >q()
| 
| // reload R
| >library(rdevelhelp)
| >load("x.RData")
| > ### here comes the problem...
| > x$greet()
| Error in .External(list(name = "CppMethod__invoke_notvoid", address =
| <pointer: 0x0>,  :
|   NULL value passed as symbol address
| >q()
| 
| ################
| 
| is there a best practice to solving this problem? I have read some posts
| about external pointers and have learned a little about serialization, but
| want to make sure I am approaching the problem correctly.

This has been discussed several times _on the list dedicated to Rcpp
question_ ie rcpp-devel.  You could try a search such as 

    site:gmane.org rcpp-devel 'reload module'

to catch some of those.  

But in short: the load / save cycle is simply not available for Rcpp modules
objects. 
 
| Thanks for your help.

Pleasure. Hope to see you over at rcpp-devel. Subscribe before you try to post.

Dirk
 
| -Mike
| 
| 	[[alternative HTML version deleted]]
| 
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