telescope.R

cat_line <- function(...) {
  cat(..., "\n", sep = "")
}

`[.telescope`<- function(x, i) {
  message("[")
  cat_line("i = ", deparse1(i))
  cat_line("x = ", deparse1(unclass(x)))
  out <- NextMethod()
  cat_line("out = ", deparse1(unclass(out)))
  cat_line("[ end")
  structure(out, class = "telescope")
}

`[<-.telescope`<- function(x, i, value) {
  message("[<-")
  cat_line("i = ", deparse1(i))
  cat_line("x = ", deparse1(unclass(x)))
  cat_line("`*tmp*` = ", deparse1(unclass(`*tmp*`)))
  cat_line("value = ", deparse1(unclass(value)))
  out <- NextMethod()
  cat_line("out = ", deparse1(unclass(out)))
  cat_line("[<- end")
  structure(out, class = "telescope")
}

x <- structure(2:4, class = "telescope")
x[2:3][2] <- 5

## [

## i = 2:3
## x = 2:4
## out = 3:4
## [ end

## [<-

## i = 2
## x = 3:4
## `*tmp*` = 3:4
## value = 5
## out = c(3, 5)
## [<- end

## [<-

## i = 2:3
## x = 2:4
## `*tmp*` = 2:4
## value = c(3, 5)
## out = c(2, 3, 5)
## [<- end

unclass(x)

## [1] 2 3 5

x <- structure(2:4, class = "telescope")
x[3:1][2:3][2] <- 5

## [

## i = 3:1
## x = 2:4
## out = 4:2
## [ end

## [

## i = 2:3
## x = 4:2
## out = 3:2
## [ end

## [<-

## i = 2
## x = 3:2
## `*tmp*` = 3:2
## value = 5
## out = c(3, 5)
## [<- end

## [<-

## i = 2:3
## x = 4:2
## `*tmp*` = 4:2
## value = c(3, 5)
## out = c(4, 3, 5)
## [<- end

## [<-

## i = 3:1
## x = 2:4
## `*tmp*` = 2:4
## value = c(4, 3, 5)
## out = c(5, 3, 4)
## [<- end

unclass(x)

## [1] 5 3 4

x <- structure(2:4, class = "telescope")
x[3:1][3:2][2:1][2] <- 5

## [

## i = 3:1
## x = 2:4
## out = 4:2
## [ end

## [

## i = 3:2
## x = 4:2
## out = 2:3
## [ end

## [

## i = 2:1
## x = 2:3
## out = 3:2
## [ end

## [<-

## i = 2
## x = 3:2
## `*tmp*` = 3:2
## value = 5
## out = c(3, 5)
## [<- end

## [<-

## i = 2:1
## x = 2:3
## `*tmp*` = 2:3
## value = c(3, 5)
## out = c(5, 3)
## [<- end

## [<-

## i = 3:2
## x = 4:2
## `*tmp*` = 4:2
## value = c(5, 3)
## out = c(4, 3, 5)
## [<- end

## [<-

## i = 3:1
## x = 2:4
## `*tmp*` = 2:4
## value = c(4, 3, 5)
## out = c(5, 3, 4)
## [<- end

unclass(x)

## [1] 5 3 4