Re: A question for my personal knowledge.

[Richard D Riehle <laoXhai@ix.netcom.com>]

In article <t7yaimcpdi.fsf@calumny.jyacc.com>,
	Hyman Rosen <hymie@prolifics.com> wrote:

>Richard D Riehle <laoXhai@ix.netcom.com> writes:
>>  For example, a properly designed C++ class requires at least one
>>  constructor, a copy constructor, overloading of assignment, and a
>>  destructor.
>
>That is completely untrue, if you mean that the programmer must supply
>those methods, since the compiler will write all of these for you if
>you don't write them yourself. You only need your own if the default
>ones are not suitable for your purposes. But for those cases, you would
>have to do the same in Ada, I imagine.

 While it is true that a C++ compiler may create _all_ of these for 
 you, it would be a rare class where there was no constructor defined
 in the public part.  I have seen C++ classes where no constructor
 was defined in which the constructor was inherited from an ancestral
 class.  Not common.  Destructors are more often defaulted to the one
 created by the compiler.  This is sometimes the source of an error
 in the design of a class.  An even more interesting source of errors
 is the failure to create a copy constructor or overload assignment. 
 You are correct that the compiler will create these for you.  The 
 question is when to create your own instead of accepting the default
 created by the compiler.  The answer to this question is often non-trivial.

 In Ada, a creation of an object is a simple declaration.  Since Ada
 allows initialization of object components, no initializor list is
 required, unless the type has a discriminant.  An Ada designer has
 some options not available to the C++ programmer when choosing which
 level of abstraction to incorporate into a design.  A prolonged 
 discussion of these is beyond the scope of a short note on this forum.
 I wonder if the closing words of your reply, "I imagine," suggest
 that further study of Ada would illuminate some of the points better
 than I could do in this brief space.  

 As to comparing the languages, such comparisons are nearly always
 fruitless.  People have their preferences.  They will find whatever
 features, syntax, and semantic horseradish that best supports their
 personal point-of-view.  This is as true of me as it no doubt is of
 you.  I use both languages, Ada and C++.  My personal preference is
 Ada.  I find it better suited to complex design of large-scale safety
 critical software.  Perhaps my preference is a function of unbridled
 bigotry.  So be it.  But I have taken the trouble to study and use
 both languages, so I think my bigotry is softened by my experience.
 Have you taken the trouble to study Ada?

 Richard Riehle
 richard@adaworks.com
 http://www.adaworks.com