Re: Ravenscar References

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 19-01-17 07:31 , J-P. Rosen wrote:
> Le 16/01/2019 à 18:48, lyttlec a écrit :
>> Can anyone suggest a good reference on using the ravenscar profile? In
>> the Ada books I have, it only gets a one or two page mention. A
>> reference with an extended case study would be great.
>>
> Did you get the official report at
> http://www.open-std.org/jtc1/sc22/wg9/n424.pdf
> ?

Note that the discussion of pragma Atomic in that document invites risky 
programming. For example, it says "All global objects that are either of 
a protected type or an atomic type may be safely shared, and so no 
static identification [to find risky, unprotected sharing] is required 
for these."

However, as I trust most of us know, while a pragma Atomic ensures that 
any read or write of the object is itself atomic, it does not ensure 
that a read-modify-write update sequence, such as X := X + 1, is atomic 
in its entirety. IMO this means that even atomic shared objects should 
be identified and the safety of their uses checked. And that using a 
protected type, with its fully atomic operations, is preferable, when 
possible.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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