Package procedure as program entry in GPR project

Package procedure as program entry in GPR project

[Jesper Quorning]

Hello All,

With the package specifikation:

package My_Program_Package is
   procedure Program_Entry_Procedure;
end My_Program_Package;

How do i make Program_Entry_Procedure as the program entry procedure in a GPR project?

I think it is possible, but can not find out how.

I know how to use a stand-alone procedure file as program entry and how to name the executable. 


Thanks from
Jesper

Re: Package procedure as program entry in GPR project

[Jere]

On Friday, January 25, 2019 at 10:12:24 AM UTC-5, Jesper Quorning wrote:
> Hello All,
> 
> With the package specifikation:
> 
> package My_Program_Package is
>    procedure Program_Entry_Procedure;
> end My_Program_Package;
> 
> How do i make Program_Entry_Procedure as the program entry procedure in a GPR project?
> 
> I think it is possible, but can not find out how.
> 
> I know how to use a stand-alone procedure file as program entry and how to name the executable. 
> 
> 
> Thanks from
> Jesper

With that specific setup, I am not sure.  But if you are willing to change
a couple of things you can do:

-- my_program_package.ads
package My_Program_Package is
   -- Notice no declaration here for the procedure, but you can put other
   -- things if you like
end My_Program_Package; 

-- my_program_package-program_entry_procedure.adb
procedure My_Program_Package.Program_Entry_Procedure is
begin
   -- your main stuff
end My_Program_Package.Program_Entry_Procedure;

Then you modify the GPR file to point to it as the main:
for Main use ("my_program_package-program_entry_procedure.adb");

I do something similar for my Gnoga GUI projects so I can have
program level stuff in the top package but have the main a child
of that top level package.

Re: Package procedure as program entry in GPR project

[Randy Brukardt]

"Jesper Quorning" <jesper.quorning@gmail.com> wrote in message 
news:9c44582e-faff-4498-88e1-c8715471e857@googlegroups.com...
> Hello All,
>
> With the package specifikation:
>
> package My_Program_Package is
>   procedure Program_Entry_Procedure;
> end My_Program_Package;
>
> How do i make Program_Entry_Procedure as the program entry procedure in a 
> GPR project?

I realize you are asking for GPR, so by definition you don't care about 
portability, but:

Ada only requires Ada implementations to support library-level procedures as 
the main. See 10.2(29). A particular implementation can allow more, but 
there is no requirement.

So if you ever might want to use some other Ada compiler (I for one, hope 
so), use such a routine.

It's trivial to write one, after all:

with My_Program_Package;
procedure My_Program_Main is
begin
    My_Program_Package.Program_Entry_Procedure;
end My_Program_Main;

                             Randy.

Re: Package procedure as program entry in GPR project

[Jesper Quorning]

I just wanted a way to avoid the trivial main file.

I also considered

package simple is
   procedure main
end simple;

package body simple is
   procedure main is
   begin
      ...
   end main;
private
   main;
end simple;

But GPR would not do that either. I will stick to the simple procedure file.


Thanks
Jesper

Re: Package procedure as program entry in GPR project

[Simon Wright]

"Randy Brukardt" <randy@rrsoftware.com> writes:

> "Jesper Quorning" <jesper.quorning@gmail.com> wrote in message 
> news:9c44582e-faff-4498-88e1-c8715471e857@googlegroups.com...
[...]
>> package My_Program_Package is
>>   procedure Program_Entry_Procedure;
>> end My_Program_Package;
>>
>> How do i make Program_Entry_Procedure as the program entry procedure
>> in a GPR project?
>
> I realize you are asking for GPR, so by definition you don't care
> about portability, but:
>
> Ada only requires Ada implementations to support library-level
> procedures as the main. See 10.2(29). A particular implementation can
> allow more, but there is no requirement.

This isn't a GPR thing, it's a GNAT thing: GNAT has no extensions here
beyond the requirement.

If you have a minimal bare-board project without any requirement for the
Ada runtime system, it's possible to do what you ask: see Maciej
Sobczak's 'Ada and SPARK on ARM Cortex-M' tutorial[1], in particular the
'First Chapter'[2].

It would be hard (and pointless) to attempt this for a program intended
to run on a typical operating system.

[1] http://www.inspirel.com/articles/Ada_On_Cortex.html
[2] http://www.inspirel.com/articles/Ada_On_Cortex_First_Program.html

Re: Package procedure as program entry in GPR project

[Simon Wright]

Simon Wright <simon@pushface.org> writes:

> in particular the 'First Chapter'[2].

ugh, read 'First Program'