[Tex/LaTex] Overruling global node style in matrix

Question

I want to build a matrix of several nodes of different types. In my example there is a matrix containing two "modules" and one "label".
For convenience I wanted to use matrix of nodes with nodes={module} since there are modules than labels.
Now, if I want to set the style of the label, I would usually use |[label]| as in:

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{matrix}
\tikzset{
    module/.style={draw, rectangle, fill=white, minimum width=4cm, minimum height=0.8cm},
    label/.style={ }
}

\begin{document}

\begin{tikzpicture}
    \matrix[fill=black!20, matrix of nodes, nodes={module}]
    {
        |[label]| Label \\ % this  doesn't produce the desired output
        Module 1        \\
        Module 2        \\
    };
\end{tikzpicture}

\end{document}

This produces:

Sure I could just specify every node explicitly, but this seems quite cumbersome. Is there a better solution?

Answer 1

As label is predefined style in TikZ, for my answer I'll use mymodule and mylabel in place of module and label.

What is happening here is that when you put nodes={mymodule} and then |[mylabel]|, the style of the cell became equivalent to |[mymodule,mylabel]|. So if mylabel/.style={} finaly the style of your cell is just like for all other cells |[mymodule]|.

As @user43963 says in his comment, you have to overwrite the properties that you don't want anymore. Like this:

\documentclass[varwidth,border=1cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}
\tikzset{
    mymodule/.style={draw, rectangle, fill=white, minimum width=4cm, minimum height=0.8cm},
    mylabel/.style={draw=none,fill=none}
}

\begin{document}

\begin{tikzpicture}
    \matrix[fill=black!20, matrix of nodes, nodes={mymodule}]
    {
        |[mylabel]| Label \\ % this  produce the different output
        Module 1        \\
        Module 2        \\
    };
\end{tikzpicture}

\end{document}