Retrieve Option Value with Function Argument Default Fallback

This function returns the value of a specified R option if it is set; otherwise, it falls back to the default value of a specified argument of a given function. The function can be identified by name only or with package qualification (e.g., "pkg::fun"). It supports arguments with default values that are constants or quoted expressions.

Usage

get_option_with_default(option_name, fun_name, arg_name)

Arguments

option_name: Character. The name of the R option to retrieve (e.g., "my_pkg_option").
fun_name: Character. The name of the function, optionally qualified with a package (e.g., "my_fun" or "mypkg::my_fun").
arg_name: Character. The name of the argument whose default value should be used as a fallback.

Value

The value of the option if set, otherwise the default value of the specified function argument. Returns NULL if the default is not accessible (e.g., for primitive or non-standard functions).

Details

Important: This function only works for standard R functions whose default argument values are accessible via formals(). It does not work for primitive functions (such as max, mean), functions implemented in C/C++, S4 methods, or functions whose defaults are not accessible programmatically.

Author

Ahmed El-Gabbas

Examples

# No option is called `.add_changed`
getOption(".add_changed")
#> NULL

# return the default value of the `.add` argument of `dplyr::group_by()`
get_option_with_default(".add_changed", "dplyr::group_by", ".add")
#> [1] FALSE

# Setting and retrieving the option
options(.add_changed = TRUE)
get_option_with_default(".add_changed", "dplyr::group_by", ".add")
#> [1] TRUE

# Removing the option, should fall back to default again
ecokit::remove_options(".add_changed")
get_option_with_default(".add_changed", "dplyr::group_by", ".add")
#> [1] FALSE

# Will return NULL for primitives:
get_option_with_default("base_max_na.rm", "base::max", "na.rm")
#> NULL