Use macro/newcommand for attributes

Question

How would one define a newcommand so that it can be used for attributes?

I have \somecommand which I can pass attributes, for example color=black in square brackets. Now I want to have a newcommand to do something like this:

\newcommand{\anewcommand}{color=black}

\begin{document}
    \somecommand[\anewcommand]
\end{document}

Although the anewcommand holds the same value as I would pass by typing it out, it doesn't work and tells me that my attributes are not defined.

Well. The \somecommand is actually the ganttbar command of the gantt.sty package. I want to have \newcommand{\person}{color=black} and then pass \person to \ganttbar[\person]. hope this clarifies it more.

MWE:

\documentclass[paper=a4,landscape]{scrartcl}
\usepackage[usenames,dvipsnames,svgnames]{xcolor}
\usepackage{gantt}

\newcommand{\person}{color=black}

\begin{document}
    \begin{gantt}[xunitlength=0.8cm,fontsize=\small,titlefontsize=\small,drawledgerline=true]{2}{7} %{# of tasks}{# of slots}
        \begin{ganttitle}
            \titleelement{week 1}{7}
        \end{ganttitle}
        \ganttbar[color=NavyBlue]{localization}{3}{3} % this works
        \ganttbar[\person]{Bla}{1}{1} % this doesn't
    \end{gantt}
\end{document}

Answer 1

Escaping the command with {} makes your MWE compilable.

However, I can't offer you insight into the inner workings. Maybe somebody else can help out here.

EDIT:

\person{} made it compilable, but as cherrung pointed out in the comments, it doesn't really solve the issue.

As a simple workaround, I'd define only the actual color-argument as a variable:

\documentclass[paper=a4,landscape]{scrartcl}
\usepackage[usenames,dvipsnames,svgnames]{xcolor}
\usepackage{gantt}

\newcommand{\person}{green}

\begin{document}
    \begin{gantt}[xunitlength=0.8cm,fontsize=\small,titlefontsize=\small,drawledgerline=true]{2}{7} %{# of tasks}{# of slots}
        \begin{ganttitle}
            \titleelement{week 1}{7}
        \end{ganttitle}
        \ganttbar[color=NavyBlue]{localization}{3}{3} % this works
        \ganttbar[color=\person]{Bla}{1}{1} % this works as well
    \end{gantt}
\end{document}