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[R-pkg-devel] import 'as' from another package

8 messages · Ben Bolker, Tim Keitt, Sebastian Meyer

Original
Tim Keitt
# 
I have

  if (!inherits(x, "RasterLayer")) x <- as(x, "RasterLayer")

in a package and its not finding the coerce definition from the raster
package. I know I need to add an @import roxygen2 directive of some kind,
but I'm not sure the correct syntax. My first try generated a warning that
it was not needed.

What is the correct way to do this? Or does raster need to export this
definition?

THK
Ben Bolker
# 
?? @importFrom methods as

?
On 7/20/20 12:06 PM, Tim Keitt wrote:
Tim Keitt
# 
It works but "check" gives
Namespace dependency not required: ?methods?

THK
On Mon, Jul 20, 2020 at 11:24 AM Ben Bolker <bbolker at gmail.com> wrote:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      Ben Bolker
    

    

      
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?? I think this is a classic confusing R message.? Try adding methods 
to the Imports: statement in your DESCRIPTION file and see if that 
helps. (Maybe I should file a bug report about that error message - it 
confuses me every time.)

        
On 7/20/20 12:34 PM, Tim Keitt wrote:

            

      
      
      
    

        

      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      Tim Keitt
    

    

      
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That did it. Thanks Ben.

THK

        
On Mon, Jul 20, 2020 at 11:36 AM Ben Bolker <bbolker at gmail.com> wrote:

        

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      Sebastian Meyer
    

    

      
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Yes, indeed, it is confusing. You don't need to file a new bug report, though. There is one already:

https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17179

Please feel free to comment there. This thread could serve as another confirmation. :-)

Best regards,
Sebastian

Am 20. Juli 2020 18:36:21 MESZ schrieb Ben Bolker <bbolker at gmail.com>:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Tim Keitt
    

    

      
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Thanks for pointing to the bug.

Now I am finding I cannot use the 'as' definitions from 'raster' without
loading the package. Do I need an @import directive that specifies the
definitions in the 'raster' package? My understanding is that the 'setAs'
function generates a 'coerce,...' signature but I'm not sure how to import
it to my package.

Thanks again.

THK

        
On Mon, Jul 20, 2020 at 2:25 PM Sebastian Meyer <seb.meyer at fau.de> wrote:

        

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
  


  


      

    

    
1 day later

    

      
      

        


  

        

      Sebastian Meyer
    

    

      
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Following WRE 1.5.6 (Namespaces with S4 classes and methods), you should
have "Depends: methods" in your DESCRIPTION, and "import(methods)" or a
more selective "importFrom(methods, ...)" directive in your NAMESPACE.

Then you would usually use the NAMESPACE directive

    importMethodsFrom(package, generic)

to explicitly import S4 methods exported from another package.
However, the raster package does not do

    exportMethods(coerce)

so if you try

    importMethodsFrom(raster, coerce)

you will get

            

      
      
      
    

        
when trying to install your package (also during R CMD check, of course).

To solve this problem, you could either

- import raster's entire NAMESPACE via import(raster)

- or ask maintainer("raster") to exportMethods(coerce)

- or do

    importClassesFrom(raster, RasterLayer)

which will magically make the corresponding coerce methods available as
well.

HTH!

	Sebastian Meyer


Am 21.07.20 um 00:41 schrieb Tim Keitt: