s7bugreport

The goal of this repository is to demonstrate a potential bug found in S7.

The bug occurs when you have an S7 class (foo) and S3 class (bar) coexisting in a package, and both classes have $-extraction methods.

library(S7)
foo <- new_class("foo", properties = list(x = new_property(class_integer, default = 10L)))

bar <- function() {
  structure(list(x = 10L), class = "bar")
}

method(`$`, foo) <- function(x, ...) {
  cat("foo $-extraction\n")
  prop(x, ...)
}

`$.bar` <- function(x, ...) {
  cat("bar $-extraction\n")
  .subset2(x, ...)
}

Both of these $-extraction methods work fine.

foo()$x
#> foo $-extraction
#> [1] 10
bar()$x
#> bar $-extraction
#> [1] 10

However, when declaring the same classes and methods from a package, the $.bar method seems to get discarded. To ensure that this is run in a clean session, I’ll use {reprex} to demonstrate. Please note in the final chunk that the "bar $-extraction" string is missing.

rpx <- reprex::reprex({
  library(s7bugreport)
  foo()$x
  bar()$x
})
#> ✖ Install the styler package in order to use `style = TRUE`.
#> ℹ Non-interactive session, setting `html_preview = FALSE`.
#> ℹ Rendering reprex...
#> CLIPR_ALLOW has not been set, so clipr will not run interactively
cat(rpx, sep = "\n")

library(s7bugreport)
foo()$x
#> foo $-extraction
#> [1] 10
bar()$x
#> [1] 10

^{Created on 2023-11-27 with reprex
v2.0.2}

hadley/s7bugreport

s7bugreport