LaTeX command for typesetting pretty-printed code blocks.

Listing.tex

% ``\Listing{...}'' command typesets its argument as a code block -
% with monospace font and whitespace preserved.  It is an
% environment-like command accepting multiple paragraphs.
\def\Listing{\bigskip\begingroup%
\setlength{\parskip}{0pc}\addtolength{\parindent}{1pc}%
\tt\scriptsize\obeylines\obeyspaces\PreserveWhitespace\ListingBody}

% ``\ListingBody'' is an auxillary command need to make Listing work.
% It inserts the argument and closes the group opened by Listing.
\long\def\ListingBody#1{#1\endgroup\smallskip}

% \PreserveWhitespace makes leading spaces appear as-is.  To make
% leading spaces appear, we have to set space to be an active
% character that exands to a non-breakable space.  The command for
% this is ``\let =\ ``, but unfortunately lifting this command to a
% macro does not quite work because space is not active during the
% definition of the macro - it needs to be made active using
% ``\catcode''.  Therefore we define our macro in a little block of
% code where space is made active:
\begingroup
\catcode32=\active
\gdef\PreserveWhitespace{\catcode32=\active\let =\ }
\endgroup