Safely call a function using ellipsis

Safely call a function using ellipsis

Usage

call_fn_ellipsis(FUN, ...)

Arguments

FUN

function that should be called with arguments in ...

...

arguments are passed to FUN() in safe manner.

Value

output from FUN() when called with relevant named arguments from ellipsis ...

Details

This function is a wrapper function intended to help pass ellipsis arguments ... from a parent function to an external function in a safe way. It will only include arguments from ... that are recognized by the external function.

The logic is described as follows:

• When the external function FUN arguments formals() include ellipsis ..., then the ellipsis ... will be passed as-is without change. In this way, any arguments inside the original ellipsis ... will either match arguments in FUN, or will be ignored in that function ellipsis ....

• When the external function FUN arguments formals() do not include ellipsis ..., then named arguments in ... are passed to FUN only when the arguments names are recognized by FUN.

Note that arguments therefore must be named.

See also

Other jam practical functions: breakDensity(), checkLightMode(), check_pkg_installed(), colNum2excelName(), color_dither(), exp2signed(), getAxisLabel(), isFALSEV(), isTRUEV(), jargs(), kable_coloring(), lldf(), log2signed(), middle(), minorLogTicks(), newestFile(), printDebug(), reload_rmarkdown_cache(), renameColumn(), rmInfinite(), rmNA(), rmNAs(), rmNULL(), setPrompt()

Examples

new_mean <- function(x, trim=0, na.rm=FALSE) {
   mean(x, trim=trim, na.rm=na.rm)
}
x <- c(1, 3, 5, NA);
new_mean(x, na.rm=TRUE);
#> [1] 3
# throws an error as expected (below)
tryCatch({
   new_mean(x, na.rm=TRUE, color="red")
}, error=function(e){
   print("Error is expected, shown below:");
   print(e)
})
#> [1] "Error is expected, shown below:"
#> <simpleError in new_mean(x, na.rm = TRUE, color = "red"): unused argument (color = "red")>

call_fn_ellipsis(new_mean, x=x, na.rm=TRUE, color="red")
#> [1] 3