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!
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