Re: ADA Objects Help!

[wilkinso@gdls.com (Robert M. Wilkinson)]

In article <D2H5un.FEr@nntpa.cb.att.com>,
Kenneth Almquist <ka@socrates.hr.att.com> wrote:
>
>C++ has two procedure calling syntaxes.  It is possible to write either
>   display(myptr);
>or
>   myptr->display();
 
Please note that these have *entirely* different semantics; they are not
merely "two forms of syntax" for the same thing. 
 
 
>These both call a procedure, passing the value myptr as the argument.
>In contrast, Ada provides only a single procedure call syntax.
>
>When you declare a procedure in C++ you specify which syntax will be
>used to call the procedure.
 
Again, there is much more to it than just the syntax.  One is a member
function, the other is a plain-old function.  Big, big, difference. 
 
 
>As a result, having the two syntaxes
>provides the following functionality:
>
>1.  Both Ada and C++ provide overloading, but in C++ it is possible for
>    two overloaded routines to have the same argument types as long as
>    the calling syntax is different.  The two calls to "display" which
>    appear above call different routines.
 
Of course they do.  One calls a member function, the other does not.  Think
of it as calling two functions with the same signature, but residing in
different packages.  
 
 
>2.  If you establish a suitable convention, the choice of calling syntax
>    can be used to convey additional information about the procedure.  I
>    haven't been able to devise a useful convention, but that doesn't mean
>    that a useful convention does not exist.
 
It is not a question of convention at all. 
 
 
>My own opinion, formed before I knew anything about Ada 9X, is that this
>functionality is not useful, and thus having two syntaxes increases the
>complexity of the language without providing any corresponding benefit.
 
Perhaps you need a better C++ book.  If you cannot see the need for 
member functions, which is the heart and soul of C++, then you definitely
do not understand the language. 
 
-- 
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Rob Wilkinson                                              wilkinso@gdls.com
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