? How get/use a 'type' from a Ada shared library loaded at run time (plugin) ?

? How get/use a 'type' from a Ada shared library loaded at run time (plugin) ?

[Daniel Norte Moraes]

Hi All!

How use Ada 'type(s)' from an library loaded at run time (dlopen &Cia)? are they possible?

My main need is to declare variables from these types or and make
dispatching calls based in these types.

Any help is welcome.

Best wishes,
Dani.

Re: ? How get/use a 'type' from a Ada shared library loaded at run time (plugin) ?

[Dmitry A. Kazakov]

On 2021-04-15 10:48, Daniel Norte Moraes wrote:

> How use Ada 'type(s)' from an library loaded at run time (dlopen &Cia)? are they possible?

Like any other type.

You should not forget to initialize the library though. The library 
project should normally have

   for Library_Auto_Init use "false";

because otherwise it would likely deadlock under Windows [if you wish to 
make your project portable]. Under Linux I am not sure if it deadlocks, 
never tested for that.

> My main need is to declare variables from these types or and make
> dispatching calls based in these types.

You cannot declare variables of types declared in a dynamically loaded 
library for the obvious reason that you cannot dynamically refer to a 
package from the library.

But you can dispatch on a class-wide object which specific type is 
declared in a dynamically loaded library.

For example you can call a dynamically loaded constructing function that 
returns T'Class where T is declared outside the library and then 
dispatch to an overridden primitive operation of S derived from T inside 
the library.

To my understanding library initialization expands dispatching tables 
with all tagged types declared in the library.

P.S. What happens on finalization is an intriguing question. I would 
rather never attempt to unload an Ada library...

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: ? How get/use a 'type' from a Ada shared library loaded at run time (plugin) ?

[Daniel Norte Moraes]

Em quinta-feira, 15 de abril de 2021 às 06:28:29 UTC-3, Dmitry A. Kazakov escreveu:
> On 2021-04-15 10:48, Daniel Norte Moraes wrote: 
> 
> > How use Ada 'type(s)' from an library loaded at run time (dlopen &Cia)? are they possible?
> Like any other type. 
> 
> You should not forget to initialize the library though. The library 
> project should normally have 
> 
> for Library_Auto_Init use "false"; 
> 
> because otherwise it would likely deadlock under Windows [if you wish to 
> make your project portable]. Under Linux I am not sure if it deadlocks, 
> never tested for that.
> > My main need is to declare variables from these types or and make 
> > dispatching calls based in these types.
> You cannot declare variables of types declared in a dynamically loaded 
> library for the obvious reason that you cannot dynamically refer to a 
> package from the library. 
> 
> But you can dispatch on a class-wide object which specific type is 
> declared in a dynamically loaded library. 
> 
> For example you can call a dynamically loaded constructing function that 
> returns T'Class where T is declared outside the library and then 
> dispatch to an overridden primitive operation of S derived from T inside 
> the library. 
> 
> To my understanding library initialization expands dispatching tables 
> with all tagged types declared in the library. 
> 
> P.S. What happens on finalization is an intriguing question. I would 
> rather never attempt to unload an Ada library... 
> 
> -- 
> Regards, 
> Dmitry A. Kazakov 
> http://www.dmitry-kazakov.de

Thanks!

Best Whishes,
Dani.