Re: Buffer PO

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 06/03/2016 06:29 AM, tonyg wrote:
> 
> I have a Fifo buffer in a protect object with a push / pop procedures and an is_empty function storing a gaggle of variant records.
> 
> I push just fine but when I come to collect my data with a pop, I have to assign it to a variable which is predeclared.
> 
> I cannot use a function as this cannot change the inside of a protected object.
> 
> Now I could use an extra buffer to contain the variant record discriminator but is there a better way?
> 
> I did think of adding a function to peek at the discriminator, but this could cause a problem as a push may change the record being viewed before my pop.

So the element type is discriminated? If the type has a default for the
discriminants, then the variable that obtains the value can be unconstrained.

If you're using Ada 12, you can use a synchronized queue rather than rolling
your own (ARM A.18.28-29). If not, the PragmAda Reusable Components have a
collection of protected queues.

-- 
Jeff Carter
"To Err is human, to really screw up, you need C++!"
Stéphane Richard
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