Re: How to get Ada to “cross the chasm”?

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

On Friday, May 4, 2018 at 3:07:40 PM UTC-4, Niklas Holsti wrote:
> On 18-05-04 16:30 , Jere wrote:
> > GNAT uses static allocation
> 
> Not universally, I think. AIUI, GNAT uses static allocation (of the size 
> of the largest variant) if the object is on the library level; stack 
> allocation for a local variable (possibly secondary stack); and (of 
> course) heap allocation if the object is dynamically allocated.
> 
sorry, I was mixing terms.  I wasn't trying to point out static lifetime, 
but more static vs dynamic allocation or maybe no-heap vs heap allocated.  
Not sure what the absolute correct term is.  I was always taught the 
terms static vs dynamic allocation, but I can see where what I said
was confusing.

 
> > The secondary stack is another example.
> 
> That is not even a standard concept in Ada, but an implementation concept.

That was kind of my point.  The language doesn't define how unconstrained
types are returned.  It could be stack or heap.  I'm not so much worried
about whether the language defines that a "secondary stack" is used or 
not but more about the practicality of how the data is passed. Sorry
about that, it was just meant to be used for example since it was an
existing implementation.  I meant no malice.

> 
> > Ada's bounded containers are another example.  As far as I can see
> > in the standard, they don't require the use of static allocation
> > and can be heap implemented by the vendor.
> 
> Yes, although IMO only an insane cross-compiler for bare metal would use 
> heap allocation for such objects (except, perhaps, when at library level).
> 

Possibly, but it would have been better if the language would have been
more explicit about it.  I can make my own, so not the end of the world.