changing visuals of code in emacs

[Andrei Alexandrescu]

Hello,


I'd like to change code visuals for the D programming language as 
follows. I'd like the construct:

Symbol!(balanced_parens)

to be visualized as:

Symbol«balanced_parens»

The chevrons should appear electrically when I type the closing ")". 
Note that balanced_parens could in turn nested use of "!()", as in 
A!(B!(C)), and they should all be paired using chevrons. The underlying 
file should not contain the chevrons, just the ASCII representation 
using "!(" and ")".

I haven't done much elisp programming beyond the common .emacs 
configuration tricks, so I don't know where to start. A few searches 
suggested that overlays may be what I'm looking for... any ideas and 
pointers? Thank you.


Andrei