Detect if Vim can show utf8 characters

Question

I have the line

set listchars=eol:↵,tab:▸-,trail:¤,nbsp:¤

in my .vimrc which I use on different machines. If the LC_CTYPE is not set to an UTF-8 map, I get the message

E474: Invalid argument: listchars=eol:�~F�,tab:�~V�-,trail:¤,nbsp:¤

How can I detect if Vim supports UTF-8? I want to do something like

if has('utf8')
    listchars=eol:↵,tab:▸-,trail:¤,nbsp:¤
else
    listchars=...
endif

Answer 1

You can test the 'encoding' option. For example I have this in my .vimrc

if &encoding == "utf-8"
    if !exists("$PUTTY_TERM") && $OS isnot# "Windows_NT"
        exe "set listchars=nbsp:\u2423,conceal:\u22ef,tab:\u2595\u2014,trail:\u02d1,precedes:\u2026,extends:\u2026,eol:\ub6"
        exe "set sbr=\u21b3"
    else
        " Putty can't display all nice utf-8 chars
        exe "set listchars=conceal:\u00b7,tab:>\u2014,trail:\u02d1,precedes:\u2026,extends:\u2026,eol:\ub6,nbsp:\u03c7"
        exe "set sbr=\u2500"
    endif
    exe "set fillchars=vert:\u2502,fold:\u2500,diff:\u2014"
else
    " Special characters that will be shown, when set list is on
    set listchars=eol:$,trail:-,tab:>-,extends:>,precedes:<,conceal:+
    " Display a `+' for wrapped lines
    set sbr=+
endif

Note also, you shouldn't change the encoding option, once it has been set, because it will invalidate all character data stored in memory in Vim.