Re: Uninitialized "out" parameters

[gauthier@unilim.fr (Michel Gauthier)]

In article <31EEACDA.64880EEB@sage.inel.gov>, Paul Whittington
<paul@sage.inel.gov> wrote:

>>  In the following Ada program, should either the compiler or the run-time
>>  get some kind of error because the out parameter is not initialized?
>>  procedure Testit is
>>    procedure SubP (op : out Integer) is
>>    begin
>>      op := op+1;
>>    end SubP;
>>    I : Integer;
>>  begin
>>    SubP (I);
>>  end Testit;

IMHO, Ada83 'out' parameters were cleanly defined, although sometimes
unpleasent when the compiler answered 'non-readable', but the Ada95 choice
is somewhat ugly (unless am I entirely mistaking), and does not correspond 
to any intuitive view of 'out'.

Here, the intuitive behaviour would be preferably raising Program_error, 
or any alternate allowed behaviour compatible with the 'non-initialised'
'bounded error'. I guess it is, which I have not checked.

This problem is harmless here, but can lead to counterintuitive results when
the type implies initialisation (records, controlled types, access types).
Intuitively, the actual parameter should be Finalize'd prior to entering the
subprogram, and re-Initialize'd as part of elaborating the declarative part
of the subprogram ___Is it the behaviour that results from LRM ?___

Apologies in advance if I am mistaking, but I guess it useful to make 'out'
clearer than it seems to be.

QUESTION : wouldn't it be worth abandoning any use of 'out' parameters ?

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