[dims] code cleanup

[JanMarvin]

library(openxlsx2)

n <- 5e5

data1 <- data.frame(
  T1 = rep("test", n),
  T2 = rep("test", n),
  T3 = rep(as.POSIXct("2024-01-01"), n),
  T4 = rep(as.POSIXct("2024-01-01"), n)
)

data2 <- data.frame(
  T1 = rep("test", n),
  T3 = rep(as.POSIXct("2024-01-01"), n),
  T2 = rep("test", n),
  T4 = rep(as.POSIXct("2024-01-01"), n)
)

fun <- function(x) {
  wb_workbook()$
    add_worksheet(
      sheet = "test",
      grid_lines = FALSE
    )$
    add_data(
      sheet = "test",
      x = x,
      na.strings = ""
    )
}

res <- microbenchmark::microbenchmark(
  fun(data1)
  ,
  fun(data2)
  ,
  times = 5
)
#> Warning in microbenchmark::microbenchmark(fun(data1), fun(data2), times = 5):
#> less accurate nanosecond times to avoid potential integer overflows

res
#> Unit: seconds
#>        expr      min       lq     mean   median       uq      max neval
#>  fun(data1) 3.862173 3.958761 4.018850 4.018531 4.088205 4.166579     5
#>  fun(data2) 4.180478 4.184563 4.464448 4.250347 4.312143 5.394709     5

This is the performance without this PR:

res
#> Unit: seconds
#>        expr      min       lq     mean   median       uq      max neval
#>  fun(data1) 3.929952 3.942532 4.212159 3.986681 4.006506 5.195121     5
#>  fun(data2) 5.501840 5.585661 5.651573 5.624333 5.699867 5.846163     5