[pstricks] Linewidth as postscript parameter

[San Kaneda]

Disclaimer: I am not a package author, and I'm not sure if I should be
answering any questions

What is your intention?

Do you want to use PS data as optional pstricks parameters?
Do you want to define the width in one place and just reuse?

\documentclass[a4paper,12pt]{article}
\usepackage[x11names]{xcolor}
\usepackage{pstricks-add}

\begin{document}
\begin{pspicture}[bgcolor=Cornsilk1](-5,-5)(5,5)
%\pstVerb{/lw 0.2 def}
\newcommand{\lw}{0.2}% something like this?
\psline[linewidth=\lw](-4,-4)(4,4)%Does not work
%\psline[linewidth=0.2](-4,-4)(4,4)%Works
\end{pspicture}
\end{document}