>>>>> Michael Lawrence <lawrence.mich...@gene.com>
>>>>> on Tue, 19 Apr 2016 05:34:41 -0700 writes:
> Not sure why R_has_methods_attached() exists. Maybe Martin could shed
> some light on that.
It was to support (via 'classgets' in attrib.c) a very fast
class(.) <- "<newclass>"
for S4 objects... to be used in setAs(......) methods,
e.g., for the Matrix package where you have many classes with
most slots the same, and I would have wanted to be clearly
faster than calling
new("<newclass>", x=.., y=.., z=.., u=..,v=.. ..)
But that experiment has not finalized, maybe because it was a too hackish idea.
I may have started writing that at a time where we still mostly
thought that it was not possible to have a working S4 R
"environment" where methods was only loaded but not attached.
In conclusion, you can consider R_has_methods_attached as non-existent.
> On Mon, Apr 18, 2016 at 11:50 PM, Kirill Müller
> <kirill.muel...@ivt.baug.ethz.ch> wrote:
>> Thanks for looking into it, your approach sounds good to me. See also
>> R_has_methods_attached()
>>
(https://github.com/wch/r-source/blob/42ecf5f492a005f5398cbb4c9becd4aa5af9d05c/src/main/objects.c#L258-L265).
>>
>> I'm fine with Rscript not loading "methods", as long as everything works
>> properly with "methods" loaded but not attached.
>>
>>
>> -Kirill
>>
>>
>>
>> On 19.04.2016 04:10, Michael Lawrence wrote:
>>>
>>> Right, the methods package is not attached by default when running R
>>> with Rscript. We should probably remove that special case, as it
>>> mostly just leads to confusion, but that won't happen immediately.
>>>
>>> For now, the S4_extends() should probably throw an error when the
>>> methods namespace is not loaded. And the check should be changed to
>>> directly check whether R_MethodsNamespace has been set to something
>>> other than the default (R_GlobalEnv). Agreed?
>>>
>>> On Mon, Apr 18, 2016 at 4:35 PM, Kirill Müller
>>> <kirill.muel...@ivt.baug.ethz.ch> wrote:
>>>>
>>>> Scenario: An S3 method is declared for an S4 base class but called for
an
>>>> instance of a derived class.
>>>>
>>>> Steps to reproduce:
>>>>
>>>>> Rscript -e "test <- function(x) UseMethod('test', x); test.Matrix <-
>>>>> function(x) 'Hi'; MatrixDispatchTest::test(Matrix::Matrix())"
>>>>
>>>> Error in UseMethod("test", x) :
>>>> no applicable method for 'test' applied to an object of class
>>>> "lsyMatrix"
>>>> Calls: <Anonymous>
>>>> 1: MatrixDispatchTest::test(Matrix::Matrix())
>>>>
>>>>> Rscript -e "extends <- 42; test <- function(x) UseMethod('test', x);
>>>>> test.Matrix <- function(x) 'Hi';
>>>>> MatrixDispatchTest::test(Matrix::Matrix())"
>>>>
>>>> [1] "Hi"
>>>>
>>>> To me, it looks like a sanity check in line 655 of src/main/attrib.c is
>>>> making wrong assumptions, but there might be other reasons.
>>>>
>>>>
(https://github.com/wch/r-source/blob/780021752eb83a71e2198019acf069ba8741103b/src/main/attrib.c#L655-L656)
>>>>
>>>> Same behavior in R 3.2.4, R 3.2.5 and R-devel r70420.
>>>>
>>>>
>>>> Best regards
>>>>
>>>> Kirill
>>>>
>>>> ______________________________________________
>>>> R-devel@r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>>
>>
>>
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