R devel - Feb 2014 - $new cannot be accessed when running from Rscript and methods package is not loaded

Hi


Accesses the $new method for a class defined in a package fails if the 
methods package is not loaded. I have created a test package with the 
following single code file:

newTest <- function() {
   cl <- get("someClass")
   cl$new
}

someClass <- setRefClass("someClass")

(This is similar to code actually used in the testthat package.)

If methods is not loaded, executing the newTest function fails in the 
following scenarios:

- Package "depends" on methods (scenario "depend")
- Package "imports" methods and imports either the setRefClass
function
(scenario "import-setRefClass") or the whole package (scenario 
"import-methods")

It succeeds if the newTest function calls require(methods) (scenario 
"require").

The script at 
https://raw2.github.com/krlmlr/methodsTest/master/test-all.sh creates an 
empty user library in subdirectory r-lib of the current directory, 
installs devtools, and tests the four scenarios by repeatedly installing 
the corresponding version of the package and trying to execute newTest() 
from Rscript. I have attached the output. The package itself is on 
GitHub: https://github.com/krlmlr/methodsTest , there is a branch for 
each scenario.

Why does it seem to be necessary to load the methods package here?


Best regards

Kirill

Because "depends" is treated incorrectly (if I may place a value
judgement on it). I had an earlier thread on this, not sure if any
changes have taken place since then:

http://r.789695.n4.nabble.com/Dependencies-of-Imports-not-attached-td4666529.html

On Mon, Feb 10, 2014 at 5:53 PM, Kirill M?ller
<kirill.mueller at ivt.baug.ethz.ch> wrote:
> Hi
>
>
> Accesses the $new method for a class defined in a package fails if the
> methods package is not loaded. I have created a test package with the
> following single code file:
>
> newTest <- function() {
>   cl <- get("someClass")
>   cl$new
> }
>
> someClass <- setRefClass("someClass")
>
> (This is similar to code actually used in the testthat package.)
>
> If methods is not loaded, executing the newTest function fails in the
> following scenarios:
>
> - Package "depends" on methods (scenario "depend")
> - Package "imports" methods and imports either the setRefClass
function
> (scenario "import-setRefClass") or the whole package (scenario
> "import-methods")
>
> It succeeds if the newTest function calls require(methods) (scenario
> "require").
>
> The script at https://raw2.github.com/krlmlr/methodsTest/master/test-all.sh
> creates an empty user library in subdirectory r-lib of the current
> directory, installs devtools, and tests the four scenarios by repeatedly
> installing the corresponding version of the package and trying to execute
> newTest() from Rscript. I have attached the output. The package itself is
on
> GitHub: https://github.com/krlmlr/methodsTest , there is a branch for each
> scenario.
>
> Why does it seem to be necessary to load the methods package here?
>
>
> Best regards
>
> Kirill
>
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

On 11 February 2014 at 02:53, Kirill M?ller wrote:
| Why does it seem to be necessary to load the methods package here?

"Just use littler (TM pending)".  

It (auto-)load methods automagically, thanks to Jeff Horner.  See below.

   edd at max:~$ chmod 0755 /tmp/kirill.r 
   edd at max:~$ /tmp/kirill.r 
   [1] "refObjectGenerator"
   attr(,"package")
   [1] "methods"
   edd at max:~$ cat /tmp/kirill.r 
   #!/usr/bin/r
   
   newTest <- function() {
      cl <- get("someClass")
      cl$new
   }

   someClass <- setRefClass("someClass")
   print(class(someClass))
   edd at max:~$ 

For Rscript, you still need to load it explicitly like any other packages you
want to use.

Dirk

PS New littler release pending in a few days or weeks. The Github repo is
current and working.

-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com