[R-pkg-devel] Any new developments on "apparent S3 method" issue?

Lenth, Russell V russell-lenth at uiowa.edu
Wed May 3 18:39:41 CEST 2017

Package developers list:

I recently added an 'as.mcmc.list' method for objects in one of my packages. Now, in doing an --as-cran check, I get this message:

* checking S3 generic/method consistency ... NOTE
Found the following apparent S3 methods exported but not registered:
See section 'Registering S3 methods' in the 'Writing R Extensions' manual.

Apparently, the checking routines conclude that I should register an 'as.mcmc' method for class "list" -- something that does not exist and is not needed. I did some searching, and found an exchange on this issue from January 2015, in which a "nonS3Method()" construct was proposed. That sure looks like what is needed, but it still doesn't exist. Is there a different way to handle this that has been developed?

Further information -- this is related to the *coda* package, and my NAMESPACE file contains this code:

if (requireNamespace("coda", quietly = TRUE)) {
    importFrom(coda, as.mcmc, as.mcmc.list)
    export(as.mcmc, as.mcmc.list)
    S3method(as.mcmc, ref.grid)
    S3method(as.mcmc.list, ref.grid)

This seems clear enough; and what's mysterious is that *coda* passes the CRAN checks without this same NOTE.

As a possible workaround, I am considering:
   -- providing and registering my own S3 method 'as.mcmc' for class "list" --- in spite of my disinterest in providing this 
  -- not importing coda::as.mcmc.list and instead exporting my own generic that handles objects of class "list" separately

Any suggestions?


Russell V. Lenth  -  Professor Emeritus
Department of Statistics and Actuarial Science   
The University of Iowa  -  Iowa City, IA 52242  USA   
Voice (319)335-0712 (Dept. office)  -  FAX (319)335-3017

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