Re: Dynamic run-time

[Tucker Taft <stt@averstar.com>]

xaplos@my-deja.com wrote:
> 
> Does Ada provide an equivalent way of realizing the dynamic behavior
> that SmallTalk or Objective-C provides? For instance is there a datatype
> like Objective-C's id that allows variables and methods to be
> dynamically bind at run-time?

Not really.  Using tagged types you can do the kind of dynamic binding
that exists in C++ or Eiffel, but not the kind of "very dynamic" binding
that you can do in SmallTalk.  The upside is that in Ada you will
never get a "message not understood."  The downside is that you
can't read in from a terminal or equivalent the name of a function
or variable and somehow find and use the named entity.  

It is possible to do things like this using a symbolic debugger, of
course, and it is possible to build tools that process the
debug tables created by the compiler and make those tables available
at run-time to the program.  This is a fair amount of work, but
I have seen it used in an Ada-based object-oriented database manager
(for a somewhat different purpose).

-- 
-Tucker Taft   stt@averstar.com   http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions  (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.)   Burlington, MA  USA