Only some foldmethods can be set in modelines?

[Erik Christiansen]

Let's take the simplest case. For each exception to my general case of
fdm = marker, I have begun to include in .vimrc e.g.:

au BufNewFile,BufRead ~/Embedded/dev_data/my_list call SimpleFold()

and one:

" Fold text blocks separated by EMPTY lines, so
" a line with whitespace unites two blocks.
function SimpleFold()
setlocal foldexpr=getline(v:lnum)=~'^$'&&getline(v:lnum+1)=~'\\S'?'<1':1
setlocal foldtext=getline(v:foldstart)
setlocal foldmethod=expr
endfunction

But that costs the labour, clutter, and maintenance nightmare of adding
a file-specific line for each file with a non-default foldmethod.

BUT, if I instead append the three lines of SimpleFold() as modelines in
the target file, then there are errors: lnum and foldstart are unknown
to Vim in modelines, at least in:

VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Apr 2 2015 20:12:09)
Included patches: 1-688

(OK, I'm on debian, so it's old. )

What I _could_ do is make the above the default fdm, and add the
following modeline to all the currently defaulted files:

vim: foldmethod=marker foldmarker={{{,}}} foldopen-=block commentstring=

That seems to work. All the previously defaulted files would come out of
the woodwork over time.

OTOH, is there a better way to do this, I can't help wondering?

Erik
(Pausing to put another log on the fire. It's midwinter down under.)

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[Nelo-Thara Wallus]

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In modelines you have to escape the colon (if your foldexpression is more
complicated than `getline(v:foldstart)` you should consider using its own
function for readability and extendability)

The best way is to give your files proper endings and to use filetype files
(`~/.vim/ftplugin/$filetype.vim`). If you use filetypes unkown to vim you have
to use a ftdetect file (`~/.vim/ftdetect/$filetype.vim`, more info[1] - it's
really just an augroup).

[1] http://learnvimscriptthehardway.stevelosh.com/chapters/44.html

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[Erik Christiansen]

On 23.07.15 13:40, Nelo-Thara Wallus wrote:
> In modelines you have to escape the colon (if your foldexpression is more
> complicated than `getline(v:foldstart)`

Many thanks. I'll try that. (In the morning. It is growing late here.)

> you should consider using its own function for readability and
> extendability)

I'll consider anything which is more elegant than the starting point,
but as ":h modeline" hammers home, no matter how many times I go back to
look, "There are two forms of modelines." I.e. Explicit and implicit
"set" directives. Nothing else.

If you can suggest how to invoke from a modeline, the function I've
already been using, listed in the post to which you replied, then I'd be
both impressed and appreciative.

> The best way is to give your files proper endings and to use filetype files
> (`~/.vim/ftplugin/$filetype.vim`). If you use filetypes unkown to vim you have
> to use a ftdetect file (`~/.vim/ftdetect/$filetype.vim`, more info[1] - it's
> really just an augroup).

That looks like a value judgement from here. ;-)
It is not the *nix way, and seems to me a right royal PITA to
administer. Using a suffix identifying foldmethod seems a very limiting
solution, since that excludes other custom handling, unless multiple
suffixes are added to the filenames. (They'd then be modelines on the
outside of the file.) Alternatively, generating a different suffix for
each of my files is easy enough I suppose, since any random guff would
do, and will handle 238328 files, just using [a-zA-Z0-9]. But that is
merely an externally visible alternative to all the autocommands I
deprecated in my OP. And generating a filetype file for each text file
would have me thinking I'm on a Mac.

I'm very happy with using modelines. It's rather like *nix file magic,
just much more customisable, and can be tacked on the end of the file
in order to be less intrusive.

For the moment, I'm experimenting with a modeline of:

vim: foldmethod=marker foldopen-=block foldtext=MyFoldText() commentstring=

and the contents of the function in the OP as default. So long as I
don't come up with a complex third alternative, that works. It does
force me to add a modeline of " vim: foldmethod=manual" in files not
using folding, since the new default does not implicitly handle that.

Thanks again for taking time to think about my quandary, especially when
it's midsummer up there.

Erik

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