Exceptions

[erickson@LIBRA.CS.NPS.NAVY.MIL (David Erickson)]

I have a few questions related to implementation of exceptions in Ada:

Can I assume that any block with an exception handler will require an
activation record at run-time (as will blocks with declarations, procedures,
functions and packages)?

Exception handling appears to be inherently inefficient, since the entire
dynamic chain may have to be searched, checking each activation for an
appropriate handler (including activations which have no handler). Are
there any optimizations which are normally used to improve this search
process?

Since exception declarations obey static scoping rules, but the search
for exception handlers follows dynamic links, an exception can go out of
and back into scope (see Barnes pg. 181 for an example).  How are names
resolved in such a way that two exceptions with the same name, declared
in different parts of the program, do not get confused? 

I would also appreciate any references to articles which address
Ada implementation issues.

-Dave Erickson