Re: Why can't objects be static in Ada?

[Jere <jhb.chat@gmail.com>]

On Thursday, April 11, 2019 at 8:40:40 AM UTC-4, Lucretia wrote:
> Someone sent in a pull request to my bindings and had to change a few constants to functions because objects can't be static. For an example:
> 
>    type Sizes is
>       record
>          Width  : Dimension;
>          Height : Dimension;
>       end record with
>      Convention => C;
> 
>    Zero_Size : constant Sizes := (others => Natural_Dimension'First);
> 
> Why can't Zero_Size be compiled as static in this pre-elaborated package?
> 
> This seems to be a major flaw in Ada imo.
> 
> Luke.

Out of curiosity, are you looking for something more akin to C++'s
constexpr [1][2] keyword?  Ada's static definition is kind of like that, 
but not as flexible or usable yet.  I'm hoping that at some point Ada 
does adjust the definition of static to be even more useful.  Most 
compiler's do make things that are static potentially
compile time, but I (think) I share your frustration in how limited
the definition actually covers, especially in places where it would
be obvious for the compiler to make that decision (well assuming the
language definition would allow it).  I think Ada202x is looking at
improving the breadth of situations for static functions (maybe someone
more versed can confirm this either way).

This is definitely one of the few outliers in my embedded code as
I work to move my old C++ embedded code into Ada designs.  It's really
frustrating to take such large hits on either performance (when dealing 
with small embedded boards) or better reusable design.  Granted it is 
just a few outliers and I can find workarounds, but the workarounds
occasionally can be more error prone and much more difficult to 
maintain.

[1]: https://www.geeksforgeeks.org/understanding-constexper-specifier-in-c/
[2]: https://en.cppreference.com/w/cpp/language/constexpr