Thats not how I read the code? Consider this snippet from registerS3method:
genfun <- get(genname, envir = envir)
if (.isMethodsDispatchOn() && methods::is(genfun, "genericFunction"))
genfun <- methods::finalDefaultMethod(genfun@default)
if (typeof(genfun) == "closure")
environment(genfun)
else .BaseNamespaceEnv
This is the environment where the method cache (.__S3MethodsTable__.) will be
updated. The problem hoverer, the with the default setting of
_R_S3_METHOD_LOOKUP_USE_TOPENV_AS_DEFENV_ this is *not* the environment where R
will look for the method cache. Manually injecting the entry into the method
cache of the top environment instead works like a charm.
The envir argument is just for looking up the generic function.
Best,
Taras
> On 30 Jun 2021, at 13:29, Duncan Murdoch <[email protected]> wrote:
>
> On 30/06/2021 7:23 a.m., Taras Zakharko wrote:
>> I had another glance at the code and now I’m convinced that this is the bug
>> in registerS3method(). Default R behavior (in objects.c) appears to be to
>> look for method definitions in the top environment, not the defining
>> environment, but registerS3method() registers the method in the defining
>> environment. I think registerS3method() should be changed to something like:
>
> It registers wherever you ask it to. The default is the defining environment.
>
> .S3method is the one that always uses the defining environment, since it has
> no way to override the default.
>
> Duncan Murdoch
>
>> - if (typeof(genfun) == "closure”)
>> - environment(genfun)
>> ------------
>> + if (typeof(genfun) == "closure”)
>> + if(isFALSE(Sys.getenv("_R_S3_METHOD_LOOKUP_USE_TOPENV_AS_DEFENV_”))
>> environment(genfun) else topenv(environment(genfun))
>> in order to match the behavior of do_usemethod()
>> Best,
>> Taras
>>> On 30 Jun 2021, at 12:51, Taras Zakharko <[email protected]> wrote:
>>>
>>> @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 <[email protected]> wrote:
>>>>
>>>> On Wed, Jun 30, 2021 at 5:17 AM Duncan Murdoch <[email protected]>
>>>> 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
>>>>>
>>>>> ______________________________________________
>>>>> [email protected] mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>>
>>>>
>>>>
>>>> --
>>>> Joshua Ulrich | about.me/joshuaulrich
>>>> FOSS Trading | www.fosstrading.com
>>>
>> ______________________________________________
>> [email protected] mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
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