Re: Ada access vs C/C++ pointers and references

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 18 Aug 2004 15:27:47 -0700, Keith H Duggar wrote:

> First, is it correct to say that Ada access types ore more
> similar to C++ references (T&) than they are to C/C++
> pointers (T*) ?

I wouldn't say so. References in C++ have three major uses:

1. Parameter passing mode specification:

   T& Foo (T& X);

2. Aliasing:

   T& X = *Y [123].Z ()->Baz; 

3. Mix-in:

   class Y
   {
      T& X;

In Ada only 3 is customary implemented using access types:

1. Some types are always by-copy, some are always by-reference, and for the
rest the compiler is free to choose the best. 

2. Aliasing is achieved by renaming:

   X : T renames Y(123).Z().Baz.all;

3. Only for mix-in one usually uses anonymous access types:

   type Y (X : access T) is ...
 
-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de