Right, R_has_methods_attached() uses that. Probably not the right
check, since it refers to S4 dispatch, while S4_extends() is used by
S3 dispatch.
Perhaps S4_extends() should force load the methods package? The above
example works after fixing the check to ensure that R_MethodsNamespace
is not R_GlobalEnv, but one could load a serialized S4 object and
expect S3 dispatch to work with Rscript.
On Tue, Apr 19, 2016 at 6:51 AM, Gabriel Becker <gmbecker at ucdavis.edu>
wrote:
See also .isMethodsDispatchOn, which is what trace uses to decide if the
methods package needs to be loaded.
~G
On Tue, Apr 19, 2016 at 5:34 AM, Michael Lawrence
<lawrence.michael at gene.com> wrote:
Not sure why R_has_methods_attached() exists. Maybe Martin could shed
some light on that.
On Mon, Apr 18, 2016 at 11:50 PM, Kirill M?ller
<kirill.mueller at ivt.baug.ethz.ch> wrote:
Thanks for looking into it, your approach sounds good to me. See also
R_has_methods_attached()
(
I'm fine with Rscript not loading "methods", as long as everything
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 M?ller
<kirill.mueller at ivt.baug.ethz.ch> wrote:
Scenario: An S3 method is declared for an S4 base class but called
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',
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.
(
Same behavior in R 3.2.4, R 3.2.5 and R-devel r70420.
Best regards
Kirill