[pstricks] A subtle problem with pstverb?

[Herbert Voss]

Boris Alexeev schrieb:
> I've been encountering problems drawing some pictures with PSTricks.
> I've tried to condense it down to a minimal example, and here's what I
> get:
> 
> The following outputs two dots, instead of one:
> \documentclass{article}
> \usepackage{pstricks}
> \begin{document}
> \begin{pspicture}(-1,-1)(1,1)
> \psdots(0,0)
> {}
> \pstverb{}
> \psdots(0,0)
> \end{pspicture}
> \end{document}

that is the default behaviour of LaTeX. {} is a line with an
empty group. The next linebreak is replaced by a space!
For all macros, which cannot be expanded, like \ifthenelse
you have to put a % at the end of a line.

\ifthenelse{\equal{z}{z}}{\psdots(1,1)}{} doesn't has the problem
because \psdots has an \ignorespaces at its definition.

You can use \ifx instead of \ifthenelse

\documentclass{article}
\usepackage{pstricks}
\def\zA{z}\def\zB{z}
\begin{document}

\begin{pspicture}(-1,-1)(1,1)
\psdots(0,0)
\ifx\zA\zB \else \fi
\pstverb{}
\psdots(0,0)
\end{pspicture}

\end{document}

However, it is not a PSTricks problem.

Herbert