[R] how to organize a lot of R source files

[Hao Cen]

Hi,

I wonder what is a better way to organize a lot of R source files. I have
a lot of utility functions written and store them in several source files
(e.g util1.R, util2.R,..utilN.R). I also have a master file in which the
source command is used to load all the util.R files. When I need to use
the utility functions in a new project, I create a new R file (e.g main.R)
in which I "source" the master file.

The problem with this approach is that anytime a single utility function
is modified, I need to rerun the source command in main.R to load the
master file, which loads all the utility R files via a loop over each
file. Sometimes I have to wait for 10 seconds to get them all loaded.
Sometimes I forget to run the source command. Is there a way in R to 1)
only reload the file changed (like a make utility) when I run source on
all utility files and/or even better 2)  reload the changed utility files,
when I run a command that use one of those utility functions, without the
need for me to source those files.

Not sure if packaging solves this issue because the library command has be
used every time a utility function is modified and in addition the package
has to be rebuilt. I don't worry about sharing the source files at this
moment as I am the only user of those utility files.

This may be a common issue many R users face. I wonder how other R users
solve this issue.

thanks

Jeff