Pass key option inside a macro to a TikZ drawing command

Question

I define a command with one optional key parameter. This command makes some calculations and them draws a tikzpicture. How can made my command to accept all the keys that a \draw command accept and pass them?

\newlength{\gl@blgskip}
\pgfkeys{/lineskip/.cd,
                   .default=\baselineskip,
                   .store in = \gl@blgskip@macro
}


\newcommand{\baselinegrid}[1][]
{

   \pgfkeys{lineskip,#1}
   % set length to optional parameter lineskip
   \setlength{\gl@blgskip}{\gl@blgskip@macro}

  %%% Do some calculations ...


  \begin{tikzpicture}
    \draw (0,0) -- (0,5cm);
  \end{tikzpicture}

Now I can call my commands as \baselinegrid[lineskip=3cm]. I want to do thing like \baselinegrid[lineskiip=3cm, color=red] and pass the option color to the \draw command.

Answer 1

I'm not sure what you want to do exactly but I would recommend building the length-setting code into the keys themselves so you can pass all the arguments to the tikzpicture environment directly. Such as

\documentclass{article}
\usepackage{tikz}
\makeatletter
\newlength{\gl@blgskip}
\tikzset{lineskip/.cd,
   .default=\baselineskip,
   .code={\setlength{\gl@blgskip}{#1}}
}
\newcommand{\baselinegrid}[1][]
{
  \begin{tikzpicture}[#1]
    \draw (0,0) grid (\gl@blgskip,\gl@blgskip);
  \end{tikzpicture}
}
\makeatother
\begin{document}

\baselinegrid[lineskip=3cm,color=red]

\end{document}

You don't need to put your keys in a separate namespace as long as you're not overwriting a tikz key. The .code key handler sets up a macro to handle the argument passed to it, so you don't have to .store in the argument and then call a separate macro later.

In situations such as these, I usually end up building all the code into keys such as the execute at begin/end picture so that your interface can be just \tikz[baselinegrid,lineskip=...]{}. If you explain more of what you want to see I can explain more.