Find the location of a directory at runtime to provide a default directory

Question

I want to move some scripts that I have made to some sort of standalone plugin. The content would look like

myplug/
  plugin/
  mydefaultdir/

For the scripts, I require a set of files which could have any name. Those are located in mydefaultdir/. I have a function that list the content of that directory and helps use it in the ensuing script. However, I want to leave to the user the option to select an entirely different directory than the one I am providing. For that I can use

:let g:scriptdir = get(g:, 'scriptdir', "/path/to/plug/mydefaultdir")
:call myfunc(g:scriptdir)

However, I cannot be sure where my plugin is located, and hence cannot set the /path/to/plug fixed.

I suppose I could look to rtp, but even that would fail if the user decided to rename the plugin directory.

I am assuming that there are better ways to do that (using runtimepath/runtime?). But essentially; it boils down to...

How can a plugin find where it is itself located?

Answer 1

How can a plugin find where it is itself located?

You need to expand() <sfile>. Assuming your code resides in myplug/plugin/<somefile.vim>:

# the first :h is to skip the script name;
# the second is to skip "plugin/" part
let s:mydefaultdir = expand("<sfile>:h:h") . "/mydefaultdir"
...
let g:scriptdir = get(g:, 'scriptdir', s:mydefaultdir)