Main procedure inside a package?

Main procedure inside a package?

[wojtek]

Hello,

Is it possible for the main procedure to be inside a package? The
compiler is GNAT.

--
Thanks,
Wojtek

Re: Main procedure inside a package?

[Pascal Obry]

wojtek@power.com.pl a �crit :
> Is it possible for the main procedure to be inside a package? The
> compiler is GNAT.

No, the main procedure must be a library level procedure. I think that
there is another restriction: this procedure should not have parameters
(I have no easy way to check that right now).

Pascal.

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Re: Main procedure inside a package?

[Jean-Pierre Rosen]

Pascal Obry a �crit :
> wojtek@power.com.pl a �crit :
>> Is it possible for the main procedure to be inside a package? The
>> compiler is GNAT.
> 
> No, the main procedure must be a library level procedure. I think that
> there is another restriction: this procedure should not have parameters
> (I have no easy way to check that right now).
> 

Anything can be a main subprogram (the restriction was for 83), however 
only parameterless library procedures are guaranteed to be portable:

LRM 10.2(29):
An implementation may restrict the kinds of subprograms it supports as 
main subprograms. However, an implementation is required to support all 
main subprograms that are public parameterless library procedures.

How to define the main subprogram (including the case where it is not a 
library procedure) is implementation defined, i.e. RTFM!
-- 
---------------------------------------------------------
            J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr

Re: Main procedure inside a package?

[Frank J. Lhota]

Jean-Pierre Rosen wrote:
> Anything can be a main subprogram (the restriction was for 83), however 
> only parameterless library procedures are guaranteed to be portable:
> 
> LRM 10.2(29):
> An implementation may restrict the kinds of subprograms it supports as 
> main subprograms. However, an implementation is required to support all 
> main subprograms that are public parameterless library procedures.
> 
> How to define the main subprogram (including the case where it is not a 
> library procedure) is implementation defined, i.e. RTFM!

Even for Ada 83, a main program was not required to be a parameterless 
library procedure. I recall seeing at least one validated Ada 83 
compiler that also allowed the main program to be a library level 
parameterless function returning an integer. The result of such a 
function sets the return code of the resulting process.

For both Ada 83 and Ada 95, however, the only portable form for a main 
program is a library parameterless library procedure.

Re: Main procedure inside a package?

[Robert A Duff]

Jean-Pierre Rosen <rosen@adalog.fr> writes:

> Pascal Obry a �crit :
> > wojtek@power.com.pl a �crit :
> >> Is it possible for the main procedure to be inside a package? The
> >> compiler is GNAT.
> > No, the main procedure must be a library level procedure. I think that
> > there is another restriction: this procedure should not have parameters
> > (I have no easy way to check that right now).
> 
> Anything can be a main subprogram (the restriction was for 83), however
> only parameterless library procedures are guaranteed to be portable:
> 
> LRM 10.2(29):
> An implementation may restrict the kinds of subprograms it supports as
> main subprograms. However, an implementation is required to support all
> main subprograms that are public parameterless library procedures.

True, but most Ada implementations support only the minimum required,
here -- no main functions, no parameters on main procedures, and no main
procedures nested in packages.

- Bob

Re: Main procedure inside a package?

[Martin Dowie]

wojtek@power.com.pl wrote:
> Hello,
> 
> Is it possible for the main procedure to be inside a package? The
> compiler is GNAT.

That would make your program potentially non-portable. The only form of 
main procedure" that is required to be supported is "However, an 
implementation is required to support all main subprograms that are 
public parameterless library procedures." (RM 10.2.27)
Cheers
-- Martin

Re: Main procedure inside a package?

[Martin Krischik]

wojtek@power.com.pl wrote:

> Is it possible for the main procedure to be inside a package? The
> compiler is GNAT.

No.

The compiler would not know which procedure should be main because the main
procedure can be called anything you like.

However It can be a child procedure to a package. I use this feature quite
often when I have packages just for one program. Works like this:

package My_Package is
end My_Package;

procedure My_Package.My_Main is
begin
 ....
end My_Package.My_Main;

Martin
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Ada programming at: http://ada.krischik.com

Re: Main procedure inside a package?

[Wojtek]

Thank you.

Re: Main procedure inside a package?

[Rolf]

> Is it possible for the main procedure to be inside a package? The
> compiler is GNAT.

with My_Package;
procedure Main is begin My_Package.Main; end;

Re: Main procedure inside a package?

[Sathish Veluswamy]

First u have to know that package cannot be executed directly. more
than that if u create a main procedure inside the package then the
compiler is unable to identify that main procedure and that main
procedure will be treated as a normal procedure inside that particular
package.