Re: [Q] Tools for Ada Quality and Style [LONG]

[Laurent.Guerby@enst-bretagne.fr (Laurent Guerby)]

Robert A Duff writes
: Yeah, it's pretty nice, and I use it all the time.  But let me play
: Devil's Advocate for a moment.

   Let's play ;-). I've changed the order of the original items.

: >- Customization (sometimes seen as a  nightmare for emacs user but not
: >so difficult if you read the manuals ;-).
: 
: Easy customization is a two edged sword.  It means the designer of the
: program doesn't need to make it do something reasonable by default,
: because, hey, anybody who doesn't like it can change it.  

   The "reasonable default"  remark is a  good point.  If  you look at
the evoluation of  emacs   (19.N), there's less and    less to do   to
customize, and there's  more and more stuff in  menus.  I disagree for
the "the program doesn't need ..." in a general sense, of course elisp
programmers are free to write their free code as they want ;-).

: I've done a
: small amount of Emacs-Lisp programming, and I agree, it's not all that
: difficult, but still, why should an Ada programmer have to learn how to
: program Emacs?  (Counter argument: learning Lisp, or any dialect
: thereof, is good for the soul.  ;-) )

   On  the learing  side,  "an Introduction  to  Emacs LISP" is freely
available under your favourite info mode ;-) and tailored for that.

: >- Find definition of everything (procedure, types)  since the Ada mode
: >parses gnatf outpout).
: 
: And the gnatf output is usually out of date, because there's no easy and
: fast way to keep it up to date with my latest keystrokes.
:
: >- Cross reference  tool, gnatf  (ASIS  soon, may be  integrated  under
: >emacs).
: 
: Again, how do you keep the output up to date?

   The default behaviour of the  Ada mode is  to rerun gnatf, but this
doesn't work because your file still does not contain most of the time
a correct Ada unit.  I believe that  a few things  are planned in this
area. The ASIS for GNAT will be of  some help for  the Ada mode (still
future).

   If  you're looking for  the definition which is  in the file you're
editing, the C-s and  C-r keystrokes give you a  quick way to get some
information. I also use multiple windows (or frames if my emacs is not
eating all my  display ;-) on the  buffer, one for useful declarations
(current buffer or other things), one for typing.

: >- Integrated multi language debugger gud/gdb (with a bit of experience
: >it works for tasking and distributed programming).
: 
: Gdb's understanding of Ada is still pretty immature, IMHO.  The
: integration with Emacs is nice, though.  Most of my bugs (if not caught
: at compile time) are some sort of assertion or constraint check failure
: that localized the problem pretty well (when I'm lucky!), and then the
: incorrect code is sitting right there ready to be edited.  But when I go
: beyond those simple (usual) cases, gdb gets confused.

   I don't know which version of gdb GNAT aware  you use. gdb 4.16 has
now been released and may  be a new release  of the GNAT patch will be
released  soon.  Of course gdb for  Ada is still  immature compared to
state of the art Ada  83 debuggers.  There's  some weak points in  the
current release, for variable declared in  local blocks, and a bit for
tagged types until  you're inside  a  known primitive  operation.  For
tasking and distributed systems issues, it  works better when you're a
bit aware   of the run-time  (it's useful  to  step into  the run-time
sources sometimes ;-) (also true for tagged types).

   But there's also   a big  advantage   for gdb,  multiple   language
debugging is working very well. 

   On this point, there's also  the SGI Programmer Workshop, which use
GNAT, and  an in-house debugger (not   gdb I think,  better check it),
also multiple-language (with some  interesting feature sharing between
languages).

: >- Multi sources syntactic and semantic checks with window and point on
: >error ala Turbo Pascal (with the GNAT messages in bonus).
: 
: The Devil has nothing to say here.  Yes, this is quite nice.
: 
: >- RCS or CVS support (with systematic window for log entry).

   Ok ok ;-).

: >- Pretty printer integrated (emacs font(lazy)-lock plus ps-print).
: 
: Which sometimes garbles the code.  Often enough that I can't really
: trust it to format large regions of code, without checking what it did,
: by hand.  It doesn't really understand the entire syntax of Ada
: correctly.  (I'm talking about bugs here, not just disagreements on
: formatting style.)
: 
: >- Reformater on demand (non too much intrusive).
: 
: Not sure how this is different from the first item.

   There's three different  topics here, standard code REformater, Ada
aware  editors,   and how  to   get  a   nice  PostScript   from  your
source.  Emacs can  be  used for the  three  items. There's some known
problem for the  Ada mode, but   not that much  with  the last release
(2.20). Here is my personal view on the topic :

- I don't like REformater, I prefer  on the fly helper for formatting.
An automatic tool cannot transform poor  code in good one, doesn't add
comments, correct design, etc  ... If you've to  import some code, the
best  (IMHO) is to let   is as is,  not to  cheat  about it (different
coding standard, etc ...). Of  course you've to convince your managers
if  they're using for  an automatic  tool for quality,  with a boolean
answer ;-). And re-design something can be a  big step towards quality
(with some knowndrawbacks, see the   Myhtical Man Month for  example),
but you've to plan it to see if it's cost  effective. [May be it would
be better to start an appropriate thread for this issue ;-]

- I like  the way the Ada  mode works as an  Ada aware editor.  If you
type "beghin" instead  of "begin", the word stay  in black, instead of
blue  (or violet  ;-) as  usual for  a  keyword, no   need to run  the
compiler. If you've omitted a ";",  TAB doesn't work  well on the next
line (idem  for imbricated constructs),  so you're  aware of it really
soon. And the customization of  indentation is well documented in  the
standard dot-emacs file.

- Pretty  printer: if you've  followed my  first advice, ps-print just
allow  you  to print exactly your  buffer,  so there's no problem here
(use the pstools if you want multiple columns on one sheet of paper).

   Note that every  item  here is  a matter of  taste (except annoying
bugs in your  tool ;-). There's  no  unique solution  to these issues,
only  two useful advices (from AQ&S)  : "think about  it ASAP" and "be
consistent".

: >-  ACT coding standard  (syntactic) switch plus  some tools to do some
: >minor reformatings.
: 
: Last time I checked, the ACT coding standard wasn't documented very well
: -- you have to guess what it is by looking at existing code, and dealing
: with error messages from the style checker.

   I think (old post from Robert Dewar) that the plan is to separate a
general purpose flag (casing consistency and things like that) and the
*internal* ACT style flag.  As the ACT standard  is likely change, you
can  use  it  for  useful advices,  but   madate it   is  tricky.  For
documentation, here is the source (opt.ads from my beta version) :

   Style_Check : Boolean := False;
   --  GNAT, GNATF
   --  Set True to perform style checks. Activates checks carried out
   --  in package Style (see body of this package for details of checks)

: >   Of course it's worth every  penny ;-). ...
: 
: Agreed.  I use it every day!  ;-)

   There's a mailing   list  for  Ada  mode  issues   (user  feedback,
configuration, releases, request for  improvements), you can get  more
information  from  my home  page about  these issues  with some useful
advices (file conf.html, see my signature for URL).

: - Bob

-- 
--  Laurent Guerby, student at Telecom Bretagne (France), Team Ada.
--  "Use the Source, Luke. The Source will be with you, always (GPL)."
--  http://www-eleves.enst-bretagne.fr/~guerby/ (GATO Project).
--  Try GNAT, the GNU Ada 95 compiler (ftp://cs.nyu.edu/pub/gnat).