Environment that obeys spaces

Question

I need to build one environment that obeys spaces, but not new lines, and also change tabulation into four spaces.

I can't use verbatim because I would also like to use macros in my environment.

Answer 1

The alltt environment from the package of the same name in the base distribution does most of that. For tab characters do you always want them to be four spaces (easy) or to tab to the next multiple of 4 (possible, but probably best handled by your editor)

Answer 2

I would tackle this by making spaces and tabs active. You could do this directly, but using the 'lower case trick' is my favoured approach:

\documentclass{article}
\begingroup
\catcode`\@=\active
\catcode`\!=\active
\lccode`\@=`\ % At-sign is a space
\lccode`\!=9 % Exclamation mark is a tab
\lowercase{%
  \endgroup
  \newenvironment{activespaces}{%
    \catcode`\ =\active % Space active
    \catcode 9 =\active % Tab active
    \let@=~%
    \def!{~~~~}% % Tab as four spaces
  }{%
    \par
  }
}
\begin{document}
\begin{activespaces}
Some text with active   spaces  !% That's a tab just before the "!"
More text
\end{activespaces}
Phew,   back   to normal!
\end{document}

Answer 3

For tabs you may want to use fancyvrb facilities:

\documentclass{article}
\usepackage{fancyvrb}
\begin{document}
\begin{Verbatim}[commandchars=\\\{\},tabsize=8,showtabs]
This    has tabs
\textit{even}   with \textit{italic}
\end{Verbatim}
\end{document}

The showtabs option is just to show the presence of tabs and is not necessary. The tabsize value can be any integer (default 8). You can also change the font used in the environment.