Re: Switching syntax highlighting

2015-10-28 2:52 GMT+03:00 sycc <sycc90@mail.com>:
> Hello all!
> I'm trying to write a function for switching between the current buffer
> syntax highlighting and whitespace, but I'm really new to vim scripting and
> such and am having a hard time.
> I switch to whitespace syntax highlighting and back quite frequently.
> However, it's not as simple as switching back to the buffer's filetype
> syntax because there are times when I've changed it to something else. For
> instance, data in .txt files that I visualize with different syntax
> highlighting formats depending on the situation.
>
> What I've tried is creating a buffer variable on buffer creation and then
> updating it, this is what I have so far:
>
> au BufEnter * let b:current_syntax=&syntax
> fu! SwitchHLwhitespace()
> if &syntax == "whitespace"
> let &syntax=b:current_syntax
> else
> let tmp=&syntax
> set syntax=whitespace
> let b:current_syntax=tmp
> endif
> endfunction
>
> This works pretty well until I open a second buffer, either with split,
> newtab or whatever.
> Now onto the questions...
> 1) If I don't use the tmp variable, somewhere inside the "set syntax"
> routine the buffer var b:current_syntax disappears. I'm not entirely sure
> why this happens, is it normal? For instance, right after opening a file I
> can do "echo b:current_syntax" and get the correct output, then I call my
> function and then once again the echo command and now it fails with
> 'Undefined variable'. Why is this?
> 2) When opening a second buffer (lets name the A and B), if I call this on A
> and switch it to whitespace, then B and switch it as well, then back to A I
> can no longer go back, the buffer var has changed to "whitespace" and no
> longer contains the stored syntax highlighting.

*Don't* use b:current_syntax name. It has special meaning, see :h
b:current_syntax-variable. Specifically after `set syntax=whitespace`
it must be set to `whitespace`.

You need to use buffer variable which has no special meaning.

>
> Now, I'm pretty sure I'm missing something important here... given that I'm
> pretty new to vim scripting and such. I was under the impression that b:
> variables were local to buffers, so I thought I could create one per opened
> buffer and this would work, does it not behave like this?
>
> Thank you all for your help!!
>
> -- Sycc
>
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