`rlang::exec` fails with `WRS2::rmmcp`

Question

I have never had issues with rlang::exec, but it mysteriously seems to fail with WRS2::rmmcp and I am not sure why or how to solve it.

# setup
set.seed(123)
library(WRS2)
library(rlang)

# works
WRS2::rmmcp(
  y = WineTasting$Taste,
  groups = WineTasting$Wine,
  blocks = WineTasting$Taster
)
#> Call:
#> WRS2::rmmcp(y = WineTasting$Taste, groups = WineTasting$Wine, 
#>     blocks = WineTasting$Taster)
#> 
#>                    psihat ci.lower ci.upper p.value p.crit   sig
#> Wine A vs. Wine B 0.02143 -0.02164  0.06449 0.19500 0.0500 FALSE
#> Wine A vs. Wine C 0.11429  0.02148  0.20710 0.00492 0.0169  TRUE
#> Wine B vs. Wine C 0.08214  0.00891  0.15538 0.00878 0.0250  TRUE

# doesn't work
rlang::exec(
  .fn = WRS2::rmmcp,
  y = WineTasting$Taste,
  groups = WineTasting$Wine,
  blocks = WineTasting$Taster
)
#> Error in names(x) <- value: 'names' attribute [18] must be the same length as the vector [3]

Why does this fail and how to solve it?

Answer 1

One alternative to exec is to construct the call by hand and then evaluate it:

mycall <- rlang::call2( "rmmcp", .ns="WRS2",
                       y = quote(WineTasting$Taste),
                       groups = quote(WineTasting$Wine),
                       blocks = quote(WineTasting$Taster) )
# WRS2::rmmcp(y = WineTasting$Taste, groups = WineTasting$Wine,
#     blocks = WineTasting$Taster)

eval(mycall)   # Works