If you are building your own modules or called codebase, it is common to split some huge functions as independent files. In other words, you may source functions in functions.
In my case, I have a file named codebase, which includes many short functions. Also, I built some huge modules based on the codebase. However, when I keep improving the codebase, it is hard to update all huge modules to support the latest version of the codebase. So, the following code is really useful. Besides, it’s a great way to prevent conflicts for the same name functions.
source('D:/Projects/Function/function_1.R', encoding = "UTF-8", local = TRUE)