dynamically source a file in R

dynamicsource.R

# Source a file in the same directory as the script regardless of the
# working directory from which the script is being called.
# Works in conjunction with argparser.
# Adapted from http://stackoverflow.com/a/1815743

command <- commandArgs(trailingOnly = FALSE)
script_name <- sub("--file=", "", command[grep("--file=", command)])
script_path <- dirname(script_name)
my_functions <- file.path(script_path, "functions.R")
source(my_functions, chdir = TRUE)