2011/3/24 Aditya Mahajan <adityam@umich.edu>

\getdate would return os.date("%Y-%m-%d",attr.modification)
and
\getdate{"long"} would return os.date("%Y-%m-%d
%H:%M",attr.modification)

I have looked at lua, but do not see how to do it. (Something else to
learn.)

I would like to do something like the following:

Untested:

\def\getdate%
{\dosinglegroupempty\dogetdate}

\def\dogetdate#1%
{context{modification_date("\jobname.tex", "#1")}}

and then in the lua code

function modification_date(file, format)
....
if format == "long" then
....
else
...
end

end

I have:
\startluacode
function modification_date(file, format)
    local f    = file
    local attr = lfs.attributes(f)

    assert (type(attr) == "table")
    if attr.mode ~= "directory" then
      if format == "long" then
        return os.date("%Y-%m-%d %H:%M",attr.modification)
      else
        return os.date("%Y-%m-%d",attr.modification)
      end
    end
end
\stopluacode

\def\getdate%
{\dosinglegroupempty\dogetdate}

\def\dogetdate#1%
{context{modification_date("\jobname.tex", "#1")}}

This results in:
contextmodification_date("subversion.tex", "")