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Newsgroups: comp.lang.ada
Date: Sun, 19 Sep 2021 17:31:26 -0700 (PDT)
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Subject: Re: Custom Storage Pool questions
From: Jere <jhb.chat@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:62780
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Followup question cause Randy's statement (below) got me thinking:
If a compiler is allowed to break up an allocation into multiple
calls to Allocate (and of course Deallocate), how does one go about
enforcing that the user's header is only created once?  In the example
Randy gave (unconstrained arrays), in Janus there is an allocation for the 
descriptor and a separate allocation for the data.  If I am making a storage
pool that is intending to create a hidden header for my objects, this means
in Janus Ada (and potentially other compilers) I would instead create two
headers, one for the descriptor and one for the data, when I might intend
to have one header for the entire object. 

On Monday, September 13, 2021 at 1:29:39 AM UTC-4, Randy Brukardt wrote:
> Not sure what you are expecting. There is no requirement that objects are 
> allocated contigiously. Indeed, Janus/Ada will call Allocate as many times 
> as needed for each object; for instance, unconstrained arrays are in two 
> parts (descriptor and data area). 
> 
> <SNIPPED>
> 
> Randy. 
> 
> 
> "Jere" <> wrote in message 
> news:e3c5c553-4a7f-408a...@googlegroups.com...
> >I was learning about making user defined storage pools when 
> > I came across an article that made me pause and wonder how 
> > portable storage pools actually can be. In particular, I assumed 
> > that the Size_In_Storage_Elements parameter in the Allocate 
> > operation actually indicated the total number of storage elements 
> > needed. 
> > 
> > <SNIPPED>
> >