What about:

\def\Var#1#2{'\type{#1}%
\directlua{
if "#2" == "," then
  tex.sprint("#2'")
else
  tex.sprint("'#2")
end}}

\Var{555}, hello \Var{666}. \Var{666}\par


On Fri, Jan 08, 2010 at 09:27:37AM -0700, Tad Ashlock wrote:
> Hi All,
> 
> I'm trying to create a command that will apply a consistent style to
> a word or phrase.  For example, when documenting source code, I'd
> like to be able to mark variables with \Var{var_name}.  Then if I
> want the variable names to be in mono, I can \def\Var#1{\type{#1}}.
> No problem there.  If I want variable names to be in quotes, then
> \def\Var#1{\quote{#1}}.
> 
> The problem is that in my ConTeXt code I'd write "This is
> \Var{var_name}, a variable."  Which would get typeset as "This is
> 'var_name', a variable." where punctuation convention (at least in
> American English) would have the comma inside the quote like this:
> "This is 'var_name,' a variable."
> 
> I've tried four different ways of implementing this, but none of
> them work consistently.  Here's my last attempt:
> 
> ==========================
> \startluacode
> function move_end_punctuation (text, punc, cmd_start, cmd_mid, cmd_end)
>    context(cmd_start .. text .. cmd_mid)
>    if string.find('.,!?', punc, 1, true) then
>        context(punc .. cmd_end)
>    else
>        context(cmd_end .. ' ' .. punc)
>    end
> end
> \stopluacode
> 
> \def\Var#1#2{\ctxlua{move_end_punctuation([==[#1]==],[==[#2]==],
>    '\\quote{\\type{','}','}')}}
> 
> \starttext
> 
> This is \Var{var_name}, a variable.
> 
> \stoptext
> ==========================
> 
> This works, until the \Var{} macro appears in the argument of
> another macro.  For example, make the text:
> 
> \framed{This is \Var{var_name}, a variable.}
> 
> and the following error results:
> ==========================
> systems         : begin file test.tex at line 16
> ! Missing $ inserted.
> <inserted text>
>                $
> <to be read again>
>                   _
> l.1 ...spaces quote{unskip  ignorespaces type{var_
>                                                  name}
> \Var ...=],[==[#2]==], '\\quote{\\type{','}','}')}
> l.18 \framed{This is \Var{var_name},
>                                     a variable.}
> ?
> ==========================
> 
> I think my problem has to do with parameter expansion, but I don't
> understand the intricacies enough to solve this.  I flailed away,
> unsuccessfully, with various combinations of \unexpanded,
> \normalunexpanded, luaescapestring, etc.
> 
> Does anyone have a solution or a pointer in the right direction?
> 
> Thank you,
> Tad
> 
> 
> 
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer