Re: Using Ada (or SPARK) in Ada-unaware environment

[Peter Amey <peter.amey@praxis-cs.co.uk>]

Maciej Sobczak wrote:
> Hi,
> 
> Imagine a control system (to be developed) which needs to interact with 
> some devices. Those devices are supplied with C drivers and libraries.
> 
> What is the recommended practice for developing this control system in 
> Ada (or SPARK)? I basically see two options for this:
> 
[snip]

I think I would probably go for a third option!  Use Ada's ability to 
interface to other languages to write an Ada boundary layer that 
interfaces to the C device drivers and provides a better and more 
abstract interface upwards to the rest of the program.  Then write the 
main control program using the new, Ada interfaces.

This mixed approach retains the beenfits of your option 1 by maximising 
the amount of Ada.  It also maintains the advantages of your option 2 
because it is still possible to test in a synthetic environment by 
providing stubs for the Ada interface layer.

Finally, it gives a degree of portability and maintainability because a 
chnage of low level device can be accommodated by rewriting the Ada 
boundary layer rather than the core application.

regards

Peter