Teaching new tricks to an old dog (C++ -->Ada)

[Turamnvia Suouriviaskimatta]

I 'm following various posting in "comp.lang. ada, comp.lang.c++ ,
comp.realtime, comp.software-eng" groups regarding selection of a
programming language of C, C++ or Ada for safety critical real-time
applications. The majority of expert/people recommend Ada for safety
critical real-time applications. I've many years of experience in C/C++ (and
Delphi) but no Ada knowledge.

May I ask if it is too difficult to move from C/C++ to Ada?
What is the best way of learning Ada for a C/C++ programmer?

[dave]

Ioannis Vranos wrote:

I can't understand why native Java would be better.

A mute point since the source has now been released, but Java
compilation into native CPU machine code, presents the most efficient
expression of the OO concept in the embedded area. Bytecode, JIT and JVM
have their place, but not in space & speed limited chips.

Most Game developers use ASM and more recently C;

And more recently (years) C++. :-)

Can't argue with your correction here, however I find it is the tool,
graphic and IDE engine vendors that are driving this. The original
engine sources tended to be C with assembler booster code (Quake,
HalfLife and derivatives). Microsoft, Nvidia, SGI (where are they now!)
and GL developer packages are offered as C++ libraries. So you are still
correct.

Schools teach Basic;

Actually I think they teach Pascal and perhaps some C. But it depends on
the countries I guess.

I can only speak to the UK and USA; and just parts therein also.
Education is in the hands of the educator. Some of my colleges are
teaching Java to 11-16 year olds, thus it would not surprise me to learn
Pascal or even C is being taught to the same age group.

Note however: there are implementations of Basic that surpass both
Pascal and C. VAX Basic, for instance, was taught in an area of Florida
I lived in. Students studied it from 11yrs through to University.

Different horses, different courses. Different countries, different
methods. Different goals....

Nme. God Bless.

[Greg Comeau]

In article <14************ ****@linux1.kri schik.com>,
Martin Krischik <ma****@krischi k.com> wrote:

...
And they havn't got 100% compliance - as the Ada compiler vendors have. And
they can indedd claim that - Ada has the ACATS test - pass the test you are
100% compliant - fail the thest and (almost) no customer will consider your
offer.

Out of curiosity how old is the ACATS test, and how many
compilers currently pass it?
--
Greg Comeau / Comeau for the Mac? Stay tuned.
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?

[Greg Comeau]

In article <45************ ****@linux1.kri schik.com>,
Martin Krischik <ma****@krischi k.com> wrote:

Ioannis Vranos wrote:

Martin Krischik wrote:

For the '98 standart yes - but how about the '03 standard. As I said -
one release behind.

C++03 is C++98 bug fixed. You can have a look at the list of fixes:

http://www.acceleratedcpp.com/author.../revisions.pdf
Ups, right C++ 2003 is only the 5 year bug fix. But then: that isn't good
news. The C++ 98 is out for 7 years and you still have to look hard to find
a fully compliant compiler.
And they havn't got 100% compliance - as the Ada compiler vendors have.

Today in the latest compiler releases of the major vendors, compliance
is at least >98% (*there are* 100% compliant implementations ).

I still look for one. Not trolling here - I would realy love to see at least
one fully compiant compiler.

As for major vendors: MS-C++ 7.1 and digital mars do not know about
"export". In my book 98% does not apply when a hole keyword is missing.

Side note: All Ada templates are "export" - so it is possible implement
export.

export was implemented in C++, a few years ago now, so it's
agree it is possible to implement export. At least Comeau C++
provides export and is "100%" compliant, whatever it is that
that means.

And
they can indedd claim that - Ada has the ACATS test - pass the test you
are 100% compliant - fail the thest and (almost) no customer will
consider your offer.

There are compliance tests for C++ too.

With ISO number? If so tell me - I love to know.

Through 3rd party commercial products.
Without ISO: better then
nothing but not as helpfull to get companies like M$ to comply.

MS has disclosed the major features that they don't support.
How would it change things?
--
Greg Comeau / Comeau for the Mac? Stay tuned.
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?

[Greg Comeau]

In article <1110655701.196 383@athnrd02>,
Ioannis Vranos <iv*@remove.thi s.grad.com> wrote:

Martin Krischik wrote:

Well actualy: since 4 is not a valid value for the enum four_val the Ada
compiler won't compile the code - Ada does not automaticy convert enums
into integer.

The way you would do it in Ada is

pragma Assert (x'Valid);

The 'Valid attribute checks if a variable contains a valid value.

Now that I am thinking of it, isn't it a value range?
int main()
{
enum four_val {a,b,c,d};

four_val x;

x = 4;
}
C:\c>g++ temp.cpp -o temp.exe
temp.cpp: In function `int main()':
temp.cpp:7: error: invalid conversion from `int' to `main()::four_v al'

In C++ but not in C it's an error, but it can also be "invalidly"
cast to the enum.
--
Greg Comeau / Comeau for the Mac? Stay tuned.
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?

[Ioannis Vranos]

Greg Comeau wrote:

Now that I am thinking of it, isn't it a value range?
int main()
{
enum four_val {a,b,c,d};

four_val x;

x = 4;
}
C:\c>g++ temp.cpp -o temp.exe
temp.cpp: In function `int main()':
temp.cpp:7: error: invalid conversion from `int' to `main()::four_v al'

In C++ but not in C it's an error, but it can also be "invalidly"
cast to the enum.

Yes, the subject in this thread is C++ and Ada. :-)

Also casting this means that you know what you are doing, and thus not
excused for mistakes. :-)

Thus you can't do that by accident.


--
Ioannis Vranos

http://www23.brinkster.com/noicys

[Martin Krischik]

Ed Falis wrote:

On Sat, 12 Mar 2005 12:46:11 -0500, CTips <ct***@bestweb. net> wrote:

For example, look at the Ada equivalent of the following code.
typedef enum {0, 1, 2, 3} four_val;
four_val x;
x = (four_val) some_int;
....
assert( x < 4);

type Four_Val is range 0 .. 3;
X : Four_Val;

pragma Volatile (X); -- ;-)
begin
X := Four_Val (Some_Int);
...
pragma Assert (X < 4, "Something is seriously honked here");
-- Currently supported by GNAT; part of Ada 2005
-- Or write your own subprogram in Ada 95 as I did for AUnit
Do_Something_Wi th (X);
Are you sure? After all 4 is not a valid value for Four_Val. I would rather
go for either:

pragma Assert (X <= Four_Val'Last, "Something is seriously honked here");

or:

pragma Assert (X'Valid, "Something is seriously honked here");
Sounds to me as though you just like to argue, because this one was pretty
silly.

Of course it is silly - mostly because the C example isn't using volatile
which you should if you fear hardware intervention - otherwise X might be
cached inside a register and you never notice the problem anyway.

Martin
--
mailto://kr******@users. sourceforge.net
Ada programming at: http://ada.krischik.com

[Martin Dowie]

Greg Comeau wrote:

In article <14************ ****@linux1.kri schik.com>,
Martin Krischik <ma****@krischi k.com> wrote:

...
And they havn't got 100% compliance - as the Ada compiler vendors have. And
they can indedd claim that - Ada has the ACATS test - pass the test you are
100% compliant - fail the thest and (almost) no customer will consider your
offer.

Out of curiosity how old is the ACATS test, and how many
compilers currently pass it?

The latest (I believe) is dated 2002 but will certainly be getting
updated to test Ada2005. See http://www.ada-auth.org/acats.html

All compiler vendors claim some level of conformance and some publish
their results. Also, all compiler vendors will have a large number of
suplimentary tests of there own. These tend to include propriatory code
from customers, so usually aren't published.

Cheers

-- Martin

[Martin Krischik]

Ioannis Vranos wrote:

Martin Krischik wrote:

Well actualy: since 4 is not a valid value for the enum four_val the Ada
compiler won't compile the code - Ada does not automaticy convert enums
into integer.

The way you would do it in Ada is

pragma Assert (x'Valid);

The 'Valid attribute checks if a variable contains a valid value.

Now that I am thinking of it, isn't it a value range?
int main()
{
enum four_val {a,b,c,d};

four_val x;

x = 4;
}
C:\c>g++ temp.cpp -o temp.exe
temp.cpp: In function `int main()':
temp.cpp:7: error: invalid conversion from `int' to `main()::four_v al'

True - C++ won't convert int to enum either without a static_cast. You know
what I realy miss in C++: dynamic_cast for discreed number:

long X = f();
short Y = dynamic_cast <short> (X);

with a throw range_error when X is to large for Y.

Yes - I have a template for that. But a template need two parameters
<from_type, to_type> and won't optimize as well as a build in function.
And with -W3 you need a lot of specialized versions to avoid all sorts of
"conditiona l ist constant" warnings.

Martin
--
mailto://kr******@users. sourceforge.net
Ada programming at: http://ada.krischik.com

[Martin Krischik]

Robert A Duff wrote:

Martin Krischik <ma****@krischi k.com> writes:

And they havn't got 100% compliance - as the Ada compiler vendors have.
And they can indedd claim that - Ada has the ACATS test - pass the test
you are 100% compliant - fail the thest and (almost) no customer will
consider your offer.

Now wait. Let's be fair. Sure, the ACATS test suite is a good thing.
But no test suite can ensure 100% compliance with the language
standard. Ada compilers do have bugs that are not caught by the ACATS!

Shure, you are right. However in the end the 100% stuff is all about
marketing - as you said - no compiler is bug free. And in fact nowadays
most of the "chosing a compiler" stuff is about marketing. Not the best
wins but the one average one with the best marketing does.

And here a CCATS and C++CATS would help a lot. Or could you imagine any Ada
vendor not submitting to running the ACATS?

Note to the C/C++ community: when we speak of ACATS we also speak of the Ada
Conformity Assessment Authority (http://www.ada-auth.org/) which actualy
runs the test. Shure anybody can run the test (i.E. with gcc you use "make
-C gcc check-ada" - you need configured gcc sources and a gcc with Ada
enabled) but that is of no marketing value.

Martin
--
mailto://kr******@users. sourceforge.net
Ada programming at: http://ada.krischik.com

[Greg Comeau]

In article <1110700112.230 910@athnrd02>,
Ioannis Vranos <iv*@remove.thi s.grad.com> wrote:

Greg Comeau wrote:

Now that I am thinking of it, isn't it a value range?
int main()
{
enum four_val {a,b,c,d};

four_val x;

x = 4;
}

C:\c>g++ temp.cpp -o temp.exe
temp.cpp: In function `int main()':
temp.cpp:7 : error: invalid conversion from `int' to `main()::four_v al'

In C++ but not in C it's an error, but it can also be "invalidly"
cast to the enum.

Yes, the subject in this thread is C++ and Ada. :-)

Also casting this means that you know what you are doing, and thus not
excused for mistakes. :-)

Thus you can't do that by accident.

*You* can not, but somebody else can :) :)
--
Greg Comeau / Comeau for the Mac? Stay tuned.
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?