Things like that:
$DoubleBrackets['[[code]]']='<pre>';
$DoubleBrackets['[[codeend]]']='</pre>';
could also be managed by new wikistyles using css-classes, no need for
extra double brackets:
%define=pre white-space:pre;%
%pre%
text here
text here
%%
(or use predefined in stdlayout.css:
.pre {white-space:pre; font-family:monospaced; }