Trouble with own macro

Question

I'm not sure where my error is. I uses this code:

\newcommand{\qr}[2]{%
  \begin{pspicture}(1.378in, 1.5in)%
    \psbarcode[]{#1}{height=1.378 width=1.378}{qrcode}%
    {\psset{unit=1.378in}\rput(0.165,0.165){\color{white}#2}}%
  \end{pspicture}%
}

The definition seems to be okay.

In this full example

\documentclass[a4paper, 12pt, parskip]{scrartcl}

\usepackage[utf8]{inputenc}
\usepackage{pst-barcode}
\usepackage{auto-pst-pdf}

\newcommand{\qr}[2]{%
  \begin{pspicture}(1.378in, 1.5in)%
    \psbarcode[]{#1}{height=1.378 width=1.378}{qrcode}%
    {\psset{unit=1.378in}\rput(0.165,0.165){\color{white}#2}}%
  \end{pspicture}%
}

\begin{document}
  \section{Demo}
  \qr{1,1}
\end{document}

I get a strange error:

! Extra \endgroup. \endpspicture ->\pst@killglue \endgroup
                                         \egroup \ifdim \wd \pst@hbox =\z@ \e... l.57   \end{pspicture}

What does this mean and how to avoid that?

Answer 1

Your command receives two mandatory arguments, so you have to use

\qr{1}{1}

Answer 2

If you must (or want to) specify the parameters in that specific (comma-separated) format, you should use something similar to this:

\documentclass{article}
\usepackage{pst-barcode}% http://ctan.org/pkg/pst-barcode

\newcommand{\qr}[1]{\qrbase(#1)}
\def\qrbase(#1,#2){%
  \begin{pspicture}(1.378in, 1.5in)%
    \psbarcode[]{#1}{height=1.378 width=1.378}{qrcode}%
    {\psset{unit=1.378in}\rput(0.165,0.165){\color{white}#2}}%
  \end{pspicture}%
}

\begin{document}
  \section{Demo}
  \qr{1,1}
\end{document}​

However, it is easier to use @Gonzalo's approach.