What's the point?

What's the point?

[The Quelisher]

If Ada95 allows dereferencing the ".all" call for pointer variables, 
then what's the point of even having a ".all" call in the first place?
Is this a carryover from Ada83 or something?
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Re: What's the point?

[Chad Bremmon]

The Quelisher wrote:
> 

It worked exactly the same way in the language 
formerly known as Ada.

There is, however, a reason.

__________________

For example: 

Pointer_a := pointer_b;

does that mean the contents of pointer a := the 
contents of pointer b or does it mean they now 
point to the same thing.  In Ada, it means that 
pointer_a and pointer_b now point to the same 
thing.  It cannot be automatically dereferenced.

However, if I want to dereference in this 
situation, I must use ".all" to dereference 
explicitly. 

Pointer_a.all := Pointer_B.all;

This will copy the contents of Pointer_b into the 
contents of pointer_a.

Chad


> If Ada95 allows dereferencing the ".all" call for pointer variables,
> then what's the point of even having a ".all" call in the first place?
> Is this a carryover from Ada83 or something?
> --
>     *.........................................*
>     .                |/                       .
>     .                |\ENDAL                  .
>     . WWW   => http://www.cs.fsu.edu/~vandyke .
>     . EMail => kendal@freenet.scri.fsu.edu    .
>     . Pager => (904) 297-6658                 .
>     .                                         .
>     *.........................................*

Re: What's the point?

[Robert Dewar]

The Quelisher said

"> If Ada95 allows dereferencing the ".all" call for pointer variables,
> then what's the point of even having a ".all" call in the first place?
> Is this a carryover from Ada83 or something?"

x.all is just like *x in C. The only difference is that in Ada you can
optionally omit the explicit deference if you select a component (e.g.
x.c can be used instead of x.all.c) or if you index an array (e.g.
x(a..b) can be used instead of x.all(a..b))