How to compile Barnes' examples from his book using GNAT

How to compile Barnes' examples from his book using GNAT

[Jerry]

How does one compile Barnes' examples from his book, Programming in Ada 2012, with GNAT? The programs are available here: cambridge.org/barnes -> Resources -> Programs.

Re: How to compile Barnes' examples from his book using GNAT

[Brian Drummond]

On Sun, 06 Dec 2015 02:49:23 -0800, Jerry wrote:

> How does one compile Barnes' examples from his book, Programming in Ada
> 2012, with GNAT? The programs are available here: cambridge.org/barnes
> -> Resources -> Programs.

It should be as simple as "gnatmake main_program.adb".

In fact it isn't ... quite. Taking the first on that list, XPROG6.txt for 
example, I see that it has to be split into .ads files for each package, 
and matching .adb files for each package body and the main program.

Tedious ... except there's a tool called "gnatchop" to do that.

So, 
gnatchop XPROG6.txt
gnatmake tower_of_hanoi.adb

Job done.

-- Brian

Re: How to compile Barnes' examples from his book using GNAT

[Jeffrey R. Carter]

On 12/06/2015 04:24 AM, Brian Drummond wrote:
> 
> So, 
> gnatchop XPROG6.txt
> gnatmake tower_of_hanoi.adb
> 
> Job done.

Almost. However, with no options, GNAT is not an Ada compiler. It doesn't insert
integer-overflow checks, stack-overflow checks, assertion checks, pre- and
post-condition checks, predicate checks, or invariant checks. The programs may
behave differently without these checks than described in the book.

In addition, it uses GNAT's static elaboration order rather than doing
elaboration as described in the ARM. This shouldn't affect the behavior of the
programs, though, so it's not really important.

The options to include all the checks in the ARM are

-gnatao -fstack-check

The option to use ARM elaboration is -gnatE.

Since we have to type options to get an Ada compiler, one might also want to use

 -gnatn -gnatwa -O2

to turn on cross-unit inlining, turn on all warnings, and perform some optimization.

The available options are described in detail in the top-secret GNAT User's Guide:

http://docs.adacore.com/gnat_ugn-docs/html/gnat_ugn/gnat_ugn.html

-- 
Jeff Carter
"I wave my private parts at your aunties."
Monty Python & the Holy Grail
13

Re: How to compile Barnes' examples from his book using GNAT

[Pascal Obry]

Jeffrey,

> Almost. However, with no options, GNAT is not an Ada compiler. It
> doesn't insert
> integer-overflow checks, 

Recent GNAT versions have overflow on by default.

> stack-overflow checks, assertion checks, pre- and
> post-condition checks, predicate checks, or invariant checks. 

The assertions and aspects checks are optional for an Ada compiler and
can be turned on and off.

-- 
  Pascal Obry /  Magny Les Hameaux (78)

  The best way to travel is by means of imagination

  http://v2p.fr.eu.org
  http://www.obry.net

  gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Re: How to compile Barnes' examples from his book using GNAT

[Jeffrey R. Carter]

On 12/06/2015 02:21 PM, Pascal Obry wrote:
> 
>> Almost. However, with no options, GNAT is not an Ada compiler. It
>> doesn't insert
>> integer-overflow checks, 
> 
> Recent GNAT versions have overflow on by default.

That's good. When I had checked not too long ago, it was still off by default.

>> stack-overflow checks, assertion checks, pre- and
>> post-condition checks, predicate checks, or invariant checks. 
> 
> The assertions and aspects checks are optional for an Ada compiler and
> can be turned on and off.

True, but examples from the book intended to demonstrate the use of these
features may not behave as described if they are not turned on.

-- 
Jeff Carter
"I wave my private parts at your aunties."
Monty Python & the Holy Grail
13

Re: How to compile Barnes' examples from his book using GNAT

[Jerry]

On Sunday, December 6, 2015 at 4:26:49 AM UTC-7, Brian Drummond wrote:
> On Sun, 06 Dec 2015 02:49:23 -0800, Jerry wrote:
> 
> > How does one compile Barnes' examples from his book, Programming in Ada
> > 2012, with GNAT? The programs are available here: cambridge.org/barnes
> > -> Resources -> Programs.
> 
> It should be as simple as "gnatmake main_program.adb".
> 
> In fact it isn't ... quite. Taking the first on that list, XPROG6.txt for 
> example, I see that it has to be split into .ads files for each package, 
> and matching .adb files for each package body and the main program.
> 
> Tedious ... except there's a tool called "gnatchop" to do that.
> 
> So, 
> gnatchop XPROG6.txt
> gnatmake tower_of_hanoi.adb
> 
> Job done.
> 
> -- Brian

Thanks, Brian. I was kind of aware of this limitation of GNAT. This makes a mess of things. Is there a preferred way that GNAT users handle this? Do they make multiple package specs and bodies in one file then let gnatchop handle it, possibly hiding the mess in another directory, or is it preferred to write the many separate spec and body files from the start?

Jerry

Re: How to compile Barnes' examples from his book using GNAT

[Jacob Sparre Andersen]

Jerry <lanceboyle@qwest.net> writes:

> Is there a preferred way that GNAT users handle this? Do they make
> multiple package specs and bodies in one file then let gnatchop handle
> it, possibly hiding the mess in another directory, or is it preferred
> to write the many separate spec and body files from the start?

The norm seems to be to put specifications and bodies in separate files
like GNAT wants them.

This seems to work with most Ada compilers, and it supports the notion
that users of a package doesn't have to look at how it is implemented.

Greetings,

Jacob
-- 
"Acupuncture: a jab well done."

Re: How to compile Barnes' examples from his book using GNAT

[Simon Wright]

Jerry <lanceboyle@qwest.net> writes:

> Is there a preferred way that GNAT users handle this? Do they make
> multiple package specs and bodies in one file then let gnatchop handle
> it, possibly hiding the mess in another directory, or is it preferred
> to write the many separate spec and body files from the start?

If I'm making a brief example, or trying to build someone else's
problematic code, I'd put the whole lot in a file
<problem>.ada. Otherwise, specs/bodies/separates all in files of their
own.

Re: How to compile Barnes' examples from his book using GNAT

[Randy Brukardt]

"Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message 
news:n42cuc$nqs$1@dont-email.me...
> On 12/06/2015 02:21 PM, Pascal Obry wrote:
>>
>>> Almost. However, with no options, GNAT is not an Ada compiler. It
>>> doesn't insert
>>> integer-overflow checks,
>>
>> Recent GNAT versions have overflow on by default.
>
> That's good. When I had checked not too long ago, it was still off by 
> default.
>
>>> stack-overflow checks, assertion checks, pre- and
>>> post-condition checks, predicate checks, or invariant checks.
>>
>> The assertions and aspects checks are optional for an Ada compiler and
>> can be turned on and off.
>
> True, but examples from the book intended to demonstrate the use of these
> features may not behave as described if they are not turned on.

I would guess that most people starting out would expect that the default 
would be for them to be on. I got caught by it writing ACATS tests. The main 
reason the language doesn't say is that we didn't want to change the 
behavior of existing compilers (many of which had pragma Assert when it was 
added to the language). But that probably is the wrong choice for 
preconditions, predicates, and so on.

                            Randy.

Re: How to compile Barnes' examples from his book using GNAT

[Jerry]

On Monday, December 7, 2015 at 2:36:45 AM UTC-7, Jacob Sparre Andersen wrote:
> Jerry writes:
> 
> > Is there a preferred way that GNAT users handle this? Do they make
> > multiple package specs and bodies in one file then let gnatchop handle
> > it, possibly hiding the mess in another directory, or is it preferred
> > to write the many separate spec and body files from the start?
> 
> The norm seems to be to put specifications and bodies in separate files
> like GNAT wants them.
> 
> This seems to work with most Ada compilers, and it supports the notion
> that users of a package doesn't have to look at how it is implemented.
> 
> Greetings,
> 
> Jacob
> -- 
> "Acupuncture: a jab well done."

It would be nice if it were possible to put multiple specs in one file and multiple bodies in another file thus maintaining interface from implementation but without a proliferation of files.

Jerry

Re: How to compile Barnes' examples from his book using GNAT

[J-P. Rosen]

Le 10/12/2015 04:26, Jerry a écrit :
> It would be nice if it were possible to put multiple specs in one
> file and multiple bodies in another file thus maintaining interface
> from implementation but without a proliferation of files.

But since you submit a /file/ to the compiler, if you change something
in one spec, all the specs get recompiled, possibly triggering a huge
cascade of (useless) recompilations.

I prefer to stick to the one-unit/one-file rule. Actually, it was
already the recommended practice before Gnat made it a requirement.

-- 
J-P. Rosen
Adalog
2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX
Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00
http://www.adalog.fr

Re: How to compile Barnes' examples from his book using GNAT

[G.B.]

On 10.12.15 09:55, J-P. Rosen wrote:
> Le 10/12/2015 04:26, Jerry a écrit :
>> It would be nice if it were possible to put multiple specs in one
>> file and multiple bodies in another file thus maintaining interface
>> from implementation but without a proliferation of files.
>
> But since you submit a /file/ to the compiler, if you change something
> in one spec, all the specs get recompiled, possibly triggering a huge
> cascade of (useless) recompilations.

It's not necessarily true that recompilation is needed if gnatmake's
-m switch does a good job:

    * Using `gnatmake' along with the `-m (minimal recompilation)'
      switch provides a mechanism for avoiding unnecessary
      recompilations. Using this switch, you can update the
      comments/format of your source files without having to recompile
      everything.

-m seems to work reasonably well when routinely using gnatchop. If
some file multi.ada has specs for procedures A and B, and I change
the spec for A by adding a parameter, I see this after changing
and saving multi.ada:

$ gnatchop -r -w -c multi.ada && gnatmake -m b
splitting multi.ada into:
    a.ads
    b.ads
gnatmake: "b" up to date.

With recent gnatmake/gcc, there also is a way now to have them
pick one unit from a file for compilation. With gnatmake,

   -eI      Index of unit in multi-unit source file

For example, using the above file with two specs in it,

$ gnatmake -gnatc -eI1 multi.ada
gcc -c -gnatc -x ada -gnateI1 -o multi~1.o multi.ada
$

Two subprogram specs in a file could be alike except for subtypes
of parameters. So, file singlefile.ada could have two almost identical
subprogram specs:

$ cat singlefile.ada

procedure A (X : Integer);

procedure A (X : Positive);
$

Using this scheme consistently, one could then see what happens
when picking one or the other subprogram for compiling a program
that calls A.

Also, for completeness, with -gnats,
  "in syntax-check-only mode (..) it is possible to check
   a file containing multiple compilation units concatenated
   together".

> I prefer to stick to the one-unit/one-file rule. Actually, it was
> already the recommended practice before Gnat made it a requirement.

With good text editors, and standard ways of handling files and
directories, there shouldn't be anything affecting compilation.
Surprisingly, there is.  (Maybe that's the effect of Unix and
MS DOS/Windows™ traditions of addressing compilation systems
and files...)