[Tex/LaTex] LuaTeX: How to handle a Lua function that prints TeX macros

Question

Let's say that I have a Lua function that prints TeX macros: How can those macros be executed during compilation with LuaLaTeX?

In the following example, I defined a LaTeX macro that should print a table (complete with the tabular environment and the actual body) through multiple tex.print calls:

% compile with LuaLaTeX
\documentclass{article}

\usepackage{array}
\newcommand{\mytable}{%
  \directlua{
    tex.print("\\begin{tabular}{lll}")
    tex.print("1 & a & Test A \\\\")
    tex.print("2 & b & Test B \\\\")
    tex.print("\\end{tabular}")
  }
}

\begin{document}
\mytable
\end{document}

However, this doesn't work. Can this be made to work or is this not the way to go at all?

Note: Actually, I define a Lua function in a myfunc.lua file, then I load it with \directlua{dofile("myfunc.lua")} and then I “pass” it to the LaTeX macro.

Related questions:

1. How to do a 'printline' in LuaTeX
2. How to manipulate a multi-line string in luatex?
3. luatex and starting TeX macros which handle new line characters

Answer 1

If using the primitive form you need to remember that like \write macros are expanded while sending to lua so you need

\documentclass{article}

\usepackage{array}
\newcommand{\mytable}{%
  \directlua{
    tex.print("\string\\begin{tabular}{lll}")
    tex.print("1 & a & Test A \string\\\string\\")
    tex.print("2 & b & Test B \string\\\string\\")
    tex.print("\string\\end{tabular}")
  }
}

\begin{document}
\mytable
\end{document}