Hi Robert,
This looks like a bug to me (tested in R 3.6.2 on Windows), f(new("a"))
should return "hi!". I'll add that this DOES work properly in 3.6.1
which leads me to suspect this could be due to the subtle change in the
way method dispatch was performed to fix a different bug, in 3.6.2. Can
anybody else confirm that?
On 2/18/2020 9:32 AM, Robert Harlow wrote:
I am trying to create a class union of class unions to facilitate method
dispatch. When I execute code in the global environment, everything acts as
expected, however when I put the same code in the context of a package,
selectMethod can no longer find the correct method. This first block below
puts the code in the context of a package:
fn <- "codefile.R"
writeLines(
c(
"setClass('x', slots = list(slot ='character'))",
"setClass('y', slots = list(slot ='character'))",
"setClass('a', slots = list(slot ='character'))",
"setClass('b', slots = list(slot ='character'))",
"setClassUnion('xy', c('x', 'y'))",
"setClassUnion('ab', c('a', 'b'))",
"setClassUnion('xyab', c('xy', 'ab'))",
"setGeneric('f', function(object, ...) standardGeneric('f'))",
"setMethod('f', 'xyab', function(object, ...) print('hi!'))"
),
con = fn
)
package.skeleton(code_files = "codefile.R")
system("rm -rf anRpackage/man")
system("R CMD INSTALL anRpackage")
library(anRpackage)
## fails in R 3.6.2, but works in R 3.5.0
f(new("a"))
Next, if a fresh R 3.6.2 session is started and I execute the following at
the prompt, method dispatch works as expected.
setClass("x", slots = list(slot ="character"))
setClass("y", slots = list(slot ="character"))
setClass("a", slots = list(slot ="character"))
setClass("b", slots = list(slot ="character"))
setClassUnion("xy", c("x", "y"))
setClassUnion("ab", c("a", "b"))
setClassUnion("xyab", c("xy", "ab"))
setGeneric("f", function(object, ...) standardGeneric("f"))
setMethod("f", "xyab", function(object, ...) print("hi!"))
## print's "hi!" as expected
f(new("a"))
I have also posted to stack overflow here:
https://stackoverflow.com/questions/60264786/r-s4-class-union-of-class-unions?noredirect=1#comment106627883_60264786,
(the example in this note removes devtools to make the environment
cleaner).
Interestingly, the issue only seems to arise when there are > 1 layer
of the class union. E.g. if I were to setMethod on "ab" instead of
"xyab", method dispatch would work as expected. I am not posting a bug
yet as it is still unclear to me if I am doing something incorrect.
My sessionInfo() is :
R version 3.6.2 (2019-12-12)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.3 LTS
Matrix products: default
BLAS: /usr/local/lib/R/lib/libRblas.so
LAPACK: /usr/local/lib/R/lib/libRlapack.so
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] anRpackage_1.0
loaded via a namespace (and not attached):
[1] compiler_3.6.2 tools_3.6.2
Thanks in advance for the help!
[[alternative HTML version deleted]]
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
