path seperator in vim

Question

I have a vim script, which uses Unix type path separator as:

"Prg: Expand snippets {{{!
let s:plugin_dir=filter(split(&rtp, ','), 'v:val =~ "/vimf90"')[0]
let s:templatedir=s:plugin_dir . '/templates/'
function! Prog(arg)
  execute 'r ' . s:templatedir . a:arg . '.txt'
  %substitute#\[:EVAL:\]\(.\{-\}\)\[:END:\]#\=eval(submatch(1))#ge
endfunction
"}}}
"

I have never used Windows, so I was not aware that it may break in Windows. One of my users reported this issue:

The script works very well on Linux system, but when I try it on Windows, it does not work with the following error:

================================================= 
Error detected while processing
C:\User\Ki-Tae\vimfiles\plugged\vimf90\ftplugin\fortran_comp.vim: line
102: E684: list index out of range: 0 E15: Invalid expression:
filter(split(&rtp, ','), 'v:val =~ "/vimf90"')[0] line 103: E121:
Undefined variable: s:plugin_dir E15: Invalid expression: s:plugin_dir
. '/templates/'
=================================================

Also, he was kind enough to send me back the solution as:

In Windows, forward slash should be backward slash, so the code should be

filter(split(&rtp, ','), 'v:val =~ "\vimf90"')[0]

and

s:plugin_dir . '\templates\'

Which he claims to work for him.

As far as I know, vim should alter the path separators inherently. But, clearly, this is not the case here.

The complete code in question is available here.

I will be grateful if someone kindly check this. I can't do that since I don't have any access to Windows.

Answer 1

Rather than explicitly specifying paths to the files you have in mind, try using built-in file path handling functions like expand() (potentially with <sfile>) or glob()/globpath().

For instance, if you're looking for the root directory of your own plugin, you might try

let s:plugin_dir = expand("<sfile>:h:h")

I'm not sure how glob will work, but you could try

let s:templatedir = glob(s:plugin_dir . '/templates')

maybe ask your user to give it a shot and tell you how it works?

Answer 2

I'd either make sure that neither / nor \ are in the &isk(momentarily), then match \<vimf90\>, or I'd match [/\\] ([/\\\\] actually because of filter()) -- I've plenty examples in path.vim module from my lh-vim-lib library plugin.

In mu-template, I didn't have your problem as I don't restrict my search for matching directories to {rtp}/somethinghardcoded/templates, but only to {rtp}/templates. This way, overriding is possible, i.e., with globpath(&rtp, 'templates') end-users will be able to override your templates in their $HOME/.vim/templates directory.