Please help with themes

[Salman Khilji]

I have a c++ class named "string".  I want to write a theme for it so that ddd 
rather than displaying it in default displays some nested member of it.  For 
example

string family
graph display family

should display:

family.rep->a

a is actually char*

family.rep->n is actually the length of the string.  I have created a gdb 
function to do it, but I want a graphical display from ddd for class with 
name "string".  I couldn't really make much sense from the manual.  Can 
someone please help me how to write a theme that would perform the equivalent 
of the following gdb function:

define printstring
       set $i=0
       set 
$out="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
       set $cur=0
       set $s = $arg0
       while $i < $s.rep->n
         set $out[$cur++] = $s.rep->a[$i++]
         if $cur >= 40
           p $out
           set $cur = 0
           set 
$out="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
         end
       end
       if $cur < 40
         p $out
       end
end