v_character_scalar() returns a validator function that checks if a value
is a single character value. This is useful as a validator function for
options managers created with create_options_manager().
v_character_scalar()A validator function that takes a value x and raises an error if:
x is not a single character value
x is an empty string
# Create a validator for non-empty character scalars
validator <- v_character_scalar()
# Valid input
validator("hello")
# Invalid inputs (would raise errors)
try(validator(c("hello", "world"))) # vector, not scalar
#> Error : must be a single character value
try(validator(123)) # numeric, not character
#> Error : must be a single character value