Re: A comparison of Ada and Modula 3

Re: A comparison of Ada and Modula 3

[Robert Dewar]

Derek asked

"How do the debuggers available for GNAT and SRC Modula-3 compare?  What about
debugging into calls to a foreign subsystem written in C or (shudder) C++?"

gdb is very happy to deal with multi-language programs, it automaticaly
switches its command interpretor personality to match the language you
ar currently debugging (e.g. you type a = b if you are debugging an
Ada unit, and (a == b) if you are debugging a C unit.

Re: A comparison of Ada and Modula 3

[AdaWorks]

Kennel (mbk@jt3ws1.etd.ornl.gov) wrote:
: Robert Dewar (dewar@cs.nyu.edu) wrote:
: > T.E.D. asks regarding implementing GC in GNAT:

: > How tough could it be?  :-)

  In embedded real-time systems, automatic garbage collection can be
  a serious liability.  Ada, the language, must work consistently over
  a wide-range of applications.  Therefore, it is appropriate that GC
  not be intrinsic to the language.

  On the other hand, Ada 95 takes the very sensible approach of including
  a package for Storage Pool management, which, when used with another
  package, Ada.Finalization, allows the developer to carefully manage the
  garbage collection processs and even make it automatic when necessary
  to the design.

  Furthermore, the Ada general access type feature eliminates many of the
  issues associated with garbage collection one found in Ada 83 because
  of the rules related to accessibility and scope.  

  Langauges that consistently do automatic garbage collection will not 
  perform correctly in embedded, hard, real-time (HRTS) weapons systems.
  They work fine, though, for desk-top systems in which safety is not an
  issue.

  Richard Riehle
  adaworks@netcom.com
-- 

richard@adaworks.com
AdaWorks Software Engineering
Suite 27
2555 Park Boulevard
Palo Alto, CA 94306
(415) 328-1815
FAX  328-1112

Re: A comparison of Ada and Modula 3

[Don Harrison]

Richard Riehle wrote:

[...]

:  Langauges that consistently do automatic garbage collection will not 
:  perform correctly in embedded, hard, real-time (HRTS) weapons systems.
:  They work fine, though, for desk-top systems in which safety is not an
:  issue.

This is certainly true for single processor architectures. There is a trend
towards parallel architectures (such as SMP - Shared Memory Processing) becoming
more affordable. When they enter mainstream computing sometime in the
not-too-distant future, background processing (such as GC) can be done on a
separate processor from the RT application proper. Then, GC will be a viable proposition for HRTS.

:  Richard Riehle
:  adaworks@netcom.com

Don.

Re: A comparison of Ada and Modula 3

[Jon S Anthony]

In article <adaworksDn32G8.14B@netcom.com> adaworks@netcom.com (AdaWorks) writes:

>   In embedded real-time systems, automatic garbage collection can be
>   a serious liability...
>...
>   Langauges that consistently do automatic garbage collection will not 
>   perform correctly in embedded, hard, real-time (HRTS) weapons systems.
>   They work fine, though, for desk-top systems in which safety is not an
>   issue.

I hope you doned your nomex suit before sending this out! :-)

/Jon
-- 
Jon Anthony
Organon Motives, Inc.
1 Williston Road, Suite 4
Belmont, MA 02178

617.484.3383
jsa@organon.com