I failed to use \newenvironment and \newcommand

Question

The following code snippet does not work.

\documentclass{article}
\usepackage{pstricks}

\newcommand\Left{-1}
\newcommand\Right{1}
\newcommand\Bottom{-1}
\newcommand\Top{1}

\newenvironment{\PsPicture}[1][]
{\begin{pspicture}[#1](\Left,\Bottom)(\Right,\Top)\ignorespaces}
{\end{pspicture}}

\newcommand\GetCoordinates{(\Left,\Bottom)(\Right,\Top)}

\begin{document}
\begin{PsPicture}[showgrid]
\end{PsPicture}

\newpage

\begin{pspicture}[showgrid]\GetCoordinates
\end{pspicture}

\end{document}

The code above is a simplified scenario that was extracted from my own document class. The idea is to avoid calling (\Left,\Bottom)(\Right,\Top) such as in

1. \pspicture(\Left,\Bottom)(\Right,\Top)
2. or \psframe(\Left,\Bottom)(\Right,\Top)

My first attempt is creating a new environment to encapsulate \pspicture, it does not work. The second attempt is creating a new command to return (\Left,\Bottom)(\Right,\Top) so hopefully it can be passed to any PSTricks macros that need (\Left,\Bottom)(\Right,\Top), it does not work as well.

How to fix it?

---

To make it clearer, I add the following code snippet

\begin{PsPicture}[showgrid]
\psframe\GetCoordinates
\end{PsPicture}

that takes advantage of \GetCoordinates so I can save some keystrokes rather than typing (\Left,\Bottom)(\Right,\Top) that is very tedious.

Answer 1

it doesn't really make sense to define such new environments/commands, they do not make things easier!

\documentclass{article}
\usepackage{pstricks}

\newcommand\Left{-1}
\newcommand\Right{1}
\newcommand\Bottom{-1}
\newcommand\Top{1}

\newenvironment{PsPicture}[1][]
{\pspicture[#1](\Left,\Bottom)(\Right,\Top)}
{\endpspicture}

\newcommand\GetCoordinates{(\Left,\Bottom)(\Right,\Top)}

\begin{document}
\begin{PsPicture}[showgrid]
\end{PsPicture}

\bigskip
\expandafter\pspicture\GetCoordinates
\psgrid[style=gridstyle]
\endpspicture

%or
\def\Temp{\pspicture[showgrid]}
\expandafter\Temp\GetCoordinates
\endpspicture

\end{document}

Answer 2

Regarding your first question: Your syntax for \newenvironment is wrong. Replace

\newenvironment{\PsPicture}[1][]

with

\newenvironment{PsPicture}[1][]

(without backslash).

Answer 3

The pspicture awaits the ( ... ) as part of its syntax and placing it inside a macro like \GetCoordinates hides it from it, which causes the issue. I would even expand the coordinates in the PsPicture environment first before passing it to pstricks, just to be on the save side.

\newenvironment{PsPicture}[1][]{%
\begingroup
\edef\@tempa{(\Left,\Bottom)(\Right,\Top)}%
\def\@tempb{\endgroup\begin{pspicture}[#1]}%
\expandafter\@tempb\@tempa
\ignorespaces}
{\end{pspicture}}