Auto-fold Perl subs

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created 2003 · complexity intermediate · author Mina Naguib · version 7.0

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The $VIMRUNTIME/syntax/perl.vim file provided with Vim has a configurable option that allows folding in Perl programs. To enable folding in files with "perl" filetype, put the following line in your vimrc (see :help perl.vim for more details):

let perl_fold = 1

The Vim 7.2 perl.vim has some bugs. A patch is available.

Alternatives

It is easier for most users to use the built-in procedure outlined above, but it is also possible to work around any issues you have with the built-in folding, using a plugin or directly writing and using a 'foldexpr'.

Plugin: SimpleFold

If you are able to install scripts, the SimpleFold script is very nice and supports Perl, among other languages.

Version 0.5 of this plugin does not support a lot of fold cases for Perl properly, however. Nevertheless, a simple patch can fix it.

About the only thing that doesn’t work is lines which both close and open a block, e.g.:

if (something) {
    stuff
} elsif (somethingelse) {                 #this doesn’t work
   otherstuff
} 

This doesn't appear simple to fix, so you're better off just adding a line break and refolding (by default it calculates and sets folds with <leader>f ).

foldexpr workaround

Add this to your vimrc to automatically fold Perl functions. You may also like to modify the script for similar languages that define a subroutine with "sub ...".

function GetPerlFold()
  if getline(v:lnum) =~ '^\s*sub\s'
    return ">1"
  elseif getline(v:lnum) =~ '\}\s*$'
    let my_perlnum = v:lnum
    let my_perlmax = line("$")
    while (1)
      let my_perlnum = my_perlnum + 1
      if my_perlnum > my_perlmax
        return "<1"
      endif
      let my_perldata = getline(my_perlnum)
      if my_perldata =~ '^\s*\(\#.*\)\?$'
        " do nothing
      elseif my_perldata =~ '^\s*sub\s'
        return "<1"
      else
        return "="
      endif
    endwhile
  else
    return "="
  endif
endfunction
setlocal foldexpr=GetPerlFold()
setlocal foldmethod=expr

See also

• Folding presents an overview of how to use folding

References

• :help folding

Comments

When let perl_fold = 1 is used, the fold method (:set fdm?) will be "syntax", and you will not be able to use manual or marker folds. If wanted, you can change the fold method, for example, :set foldmethod=manual.

In other words, if you want vim to autofold perl subroutines, use let perl_fold = 1 in your .vimrc. This should automatically set foldmethod=syntax when you load a perl file, but if not, you can manually set foldmethod=syntax or put this command in a file in $HOME/.vim/after/syntax called perl.vim (create this directory and file if it does not yet exist).

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