Access defined Lua global variables in TeX macros‏

Question

I am a newbie in LuaTeX, but it is very interesting.

Sometimes, I need process some macro arguments by Lua code, so it will be useful that if we can access the variables defined in Lua. An example:

\def\foo#1{%
  \directlua{var = [[#1]] .. " " .. system}
  % other part of this macro
  ...}

\foo{typesetting}

\bye

how can I access the var defined in the \directlua? Say, after \foo{typesetting}, I can get typesetting system by only using the var.

---

Another question is that how can I access the TeX command in \directlua environment?

Answer 1

See my answer here: Which Lua environment should I use with LuaTeX (LuaLaTeX)?

You can do this:

\newcommand\myrepeat[2]{%
\luaexec{
  for i=1,#1 do
     tex.sprint("\luatexluaescapestring{#2}")
   end
 }}

\myrepeat{4}{Hello world}

to access the macro parameters.

\newcommand\mymacro[1]{%
   \directlua{myvar=\luatexluaescapestring{#1}}}

should be enough to assign parameter 1 to the variable myvar.

For your plain TeX solution, this prints out 'typesetting system':

\def\foo#1{%
  \directlua{var = [[\luaescapestring{#1}]] .. " system"
  tex.sprint(var)
}% other part of this macro
}

\foo{typesetting}

\bye

Answer 2

I suppose you mean using the variable also outside of Lua, right?

\def\foo#1{%
  \directlua{var = "Year: " .. [[\luaescapestring{#1}]]
    tex.sprint(var)
    tex.sprint{"\string\\def\string\\var{\luaescapestring{#1}}"}
  }% other part of this macro
}

\foo{\the\year}

\var
\bye

with the output: