@Duncan: .S3method() calls registerS3method() with appropriate environmental argument under the good, so that’s not the problem.
Anyway, I’ve been doing some debugging and I think I have found the issue. The following snippet in src/objects.c (https://github.com/wch/r-source/blob/ecc633b37d77fdd1cb27dda74d7f6b3684f0c01c/src/main/objects.c#L525) sets the global lookup_use_topenv_as_defenv variable: if(lookup_use_topenv_as_defenv == -1) { lookup = getenv("_R_S3_METHOD_LOOKUP_USE_TOPENV_AS_DEFENV_"); lookup_use_topenv_as_defenv = ((lookup != NULL) && StringFalse(lookup)) ? 0 : 1; } Isn’t that supposed to be lookup_use_topenv_as_defenv = ((lookup != NULL) && StringFalse(lookup)) ? 1 : 0; instead? The way the code works right now, methods will be looked up in top environment exactly if _R_S3_METHOD_LOOKUP_USE_TOPENV_AS_DEFENV_ is not set. This seems incompatible with what registerS3method() does (setting the .__S3MethodsTable__. on the defining environment instead of the topenv). When I change 0 and 1 around, everything works as expected. In the meantime, I can work around it by manually injecting __S3MethodsTable__ into .GlobalEnv (which is my topenv here). I can open a bug report, but I would like to wait for some more comments. Best, Taras > On 30 Jun 2021, at 12:39, Joshua Ulrich <josh.m.ulr...@gmail.com> wrote: > > On Wed, Jun 30, 2021 at 5:17 AM Duncan Murdoch <murdoch.dun...@gmail.com> > wrote: >> >> On 30/06/2021 5:22 a.m., Taras Zakharko wrote: >>> Dear all, >>> >>> I have a generic function and a bunch of methods defined in a separate >>> environment. Here is a reduced example: >>> >>> env <- local({ >>> # define the generic function and the method >>> myfun <- function(x) UseMethod("myfun") >>> myfun.myclass <- function(x) print("called myfun.myclass”) >>> >>> # register the method >>> .S3method("myfun", "myclass", myfun.myclass) >>> >>> environment() >>> }) >>> >>> Since the method has been registered, I hoped that invocation like this >>> would work: >>> >>> env$myfun(structure(0, class = "myclass”)) >>> >>> However, this results in a “no applicable method" error. >>> >>> It is my understanding that registerS3method (called by .S3method) will >>> install the method string in the .__S3MethodsTable__. table of the >>> environment where the generic function is defined, and this table is >>> subsequently used by usemethod() inside R, so I am puzzled that the >>> dispatch does not work. I checked and the .__S3MethodsTable__. of env is >>> indeed setup correctly. I also tried manually adding the method string to >>> the global .__S3MethodsTable__. inside .BaseNamespaceEnv to no effect. >>> >>> In fact, the only way to make it work is to define either myfun or >>> myfun.myclas in the global environment, which is something I would like to >>> avoid. >>> >>> Thank you in advance for any pointers! >>> >> >> registerS3method has an additional parameter "envir" which I believe >> would end up set to env in your code. So this works: >> >>> eval(expression(myfun(structure(0, class = "myclass"))), envir = env) >> [1] "called myfun.myclass" >> >> You could probably also call registerS3method with envir specified >> appropriately and get your original expression to work. >> > That doesn't seem to work on 4.1.0 for me. The code below worked for > me in Oct-2020, though I'm not sure what version of R I was using at > the time. I was slow to upgrade to 4.0, so it was probably the latest > 3.x version. > > env <- new.env() > local({ > # define the generic function and the method > myfun <- function(x) { UseMethod("myfun", x) } > > # register the method > registerS3method("myfun", "myclass", > function(x) { print("called myfun.myclass") }, > envir = env) > }, envir = env) > attach(env) > myfun(structure(0, class = "myclass")) > > >> Duncan Murdoch >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > Joshua Ulrich | about.me/joshuaulrich > FOSS Trading | www.fosstrading.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel