Re: How do I get this to work??

[robert_dewar@my-dejanews.com]

In article <GIVn2.8028$Kg6.59441@news2.telusplanet.net>,
  warwicks@telusplanet.net (Chris Warwick) wrote:
> Even from my Ada83 days, the only "safe" way to do
> dynamic memory allocation was though the use of local
> variables on the stack. If I understand this concept,
> then the view is that it is better to point to a newly
> allocated buffer, then it is to point to a procedure's
> local variable.

Exactly, and the reason is to avoid aliasing. This is a
very familiar principle. Look at Pascal for example to
see the start of this thread of design thinking, which Ada
adopted. Ada 95 adds aliased variables, but they should be
used with discretion!

> Given that most Ada compilers have no way to deallocate
> memory,

That's simply wrong. Both Ada 83 and Ada 95 have a way
to deallocate dynamic memory (Unchecked_Deallocation), and
an Ada compiler not implementing this facility is
impossible to imagine (and has never existed).

> I seem to be trading the potential for a pointer to exist
> past the life of the allocated memory for a program
> continously allocates memory...

Not clear what you are saying here. Certainly pointing
to local variables on the stack has very dangerous possible
consequences with regard to dangling pointers.

The point here is that if you look at any program that
uses the keyword ALIASED extensively, then this is almost
always an example or importing C style into Ada (see
separate thread on importing Pascal into COBOL :-) and is
something that should be avoided. Almost always such code
can be written to avoid the use of ALIASED, and the result
will be improved, better structured code.

Robert Dewar

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