[Rd] S3 dispatch for S4 subclasses only works if variable "extends" is accessible from global environment

[Kirill Müller]

Please omit "MatrixDispatchTest::" from the test scripts:

Rscript -e "test <- function(x) UseMethod('test', x); test.Matrix <- 
function(x) 'Hi'; test(Matrix::Matrix())"

Rscript -e "extends <- 42; test <- function(x) UseMethod('test', x); 
test.Matrix <- function(x) 'Hi'; test(Matrix::Matrix())"


-Kirill


On 19.04.2016 01:35, Kirill Müller 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
>
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