Set R function parameters to an environment

set_function_params.R

#' Set function parameters to an environment.
#'
#' This function is designed to help debug functions. It will attempt to set all
#' the default parameter values to the specified environment (global environment
#' by default). This is useful for when you want to execute code within the
#' function definition interactively but need the parameters set in the current
#' environment.
#'
#' **Warning:** This function will modify the global environment and therefore
#' violates CRAN policy
#' ["Packages should not modify the global environment (user’s workspace)"]
#' (https://cran.r-project.org/web/packages/policies.html#Source-packages).
#'
#' @param FUN the function to assign parameters to an environment.
#' @param envir the environment to assign the variables to. Defaults to the
#'        global environment.
#' @param verbose whether to return the data frame invisibly or to print the results.
#' @return a data frame where row names correspond to the parameter name with
#'        two columns: `set` which is logical indicating if the variable was set
#'        and `value` with a character representation of the variable value.
set_function_params <- function(FUN, envir = globalenv(), verbose = interactive()) {
	params <- formals(FUN)
	params_set <- data.frame(row.names = names(params),
							 set = rep(FALSE, length(params)),
							 value = rep(NA_character_, length(params)))
	for(param in names(params)) {
		value <- params[[param]]
		if(!missing(value)) {
			if(is.character(value)) {
				assign(param, value, envir = envir)
				params_set[param,]$value <- value
			} else {
				assign(param, eval(value), envir = envir)
				params_set[param,]$value <- eval(value)
			}
			params_set[param,]$set <- TRUE
		}
	}
	if(verbose) {
		return(params_set)
	} else {
		invisible(params_set)
	}
}