Feature request: getMode() as a fast shortcut for versionInfo()$mode

[DavisVaughan]

Similar to #279

We discovered in r-lib/lifecycle#167 that cli::num_ansi_colors() is slow when called interactively in RStudio due to rstudioapi::versionInfo() being fairly slow. versionInfo() is slow due to having to call readCitationFile(), and in cli the citation bit isn't required at all. The only things it uses are the $version and the $mode.

getVersion() gives us fast (in theory, see #279) access to $version. It would be nice to also have getMode() that cli could use to have fast access to the $mode.

library(rstudioapi)

bench::mark(
  .Call("rs_rstudioProgramMode", PACKAGE = "(embedding)"),
  versionInfo()$mode
)

# A tibble: 2 × 13
  expression      min median `itr/sec` mem_alloc `gc/sec` n_itr  n_gc total_time result memory    
  <bch:expr>    <bch> <bch:>     <dbl> <bch:byt>    <dbl> <int> <dbl>   <bch:tm> <list> <list>    
1 ".Call(\"rs_… 328ns  410ns  2298553.        0B     0    10000     0     4.35ms <chr>  <Rprofmem>
2 "versionInfo… 375µs  386µs     2515.    20.6KB     8.27  1216     4   483.42ms <chr>  <Rprofmem>
# ℹ 2 more variables: time <list>, gc <list>

[TimTaylor]

@kevinushey - Sorry to be that person 😬 but do we think this and #279 are going to be implemented in the foreseeable future? Experiencing very slow (relative) tibble printing for some things which I think is again down to cli::num_ansi_colors.

[kevinushey]

Done now; on the way to CRAN.

[TimTaylor]

⭐ Thank you!