A new vector class that enables a function subsetting assignment method x[f] <- value

in_place.R

`[.vec` <- function(x, i, ...) {
  UseMethod("[.vec", i)
}

`[<-.vec` <- function(x, i, value, ...) {
  UseMethod("[<-.vec", i)
}

`[.vec.default` <- function(x, i, ...) {
  class(x) <- setdiff(class(x), "vec")
  x <- x[i]
  as_vec(x)
}

`[<-.vec.default` <- function(x, i, value, ...) {
  class(x) <- setdiff(class(x), "vec")
  x[i] <- value
  as_vec(x)
}

`[.vec.function` <- function(x, f) {
  class(x) <- setdiff(class(x), "vec")
  x <- x[f(x)]
  as_vec(x)
}

`[<-.vec.function` <- function(x, f, value) {
  class(x) <- setdiff(class(x), "vec")
  x[f(x)] <- value
  as_vec(x)
}

format.vec <- function(x, ...) {
  class(x) <- setdiff(class(x), "vec")
  format(x)
}

print.vec <- function(x, ...) {
  class(x) <- setdiff(class(x), "vec")
  print(x)
}

iseven <- function(x) {
  x %% 2 == 0
}

as_vec <- function(x) {
  class(x) <- c("vec", class(x))
  x
}

myvec <- as_vec(1:10)
myvec
#>  [1]  1  2  3  4  5  6  7  8  9 10

myvec[3]
#> [1] 3
myvec
#>  [1]  1  2  3  4  5  6  7  8  9 10

myvec[3] <- 99
myvec
#>  [1]  1  2 99  4  5  6  7  8  9 10

myvec[iseven]
#> [1]  2  4  6  8 10
myvec
#>  [1]  1  2 99  4  5  6  7  8  9 10

myvec[iseven] <- 0
myvec
#>  [1]  1  0 99  0  5  0  7  0  9  0