Re: Why C++ is successful

[eachus@spectre.mitre.org (Robert I. Eachus)]

In article <35BF49E8.136D75C2@earthling.net> Charles Hixson <charleshixson@earthling.net> writes:

 > But what Ada REALLY needs is a good garbage collection mechanism.  And
 > saying "Do it by hand" doesn't qualify as good!

   The Ada philosophy is to give the programmer the tools he needs and
to allow him the freedom to create types (classes) that do what is
required for that type.  Of course there are also predefined types and
where appropriate there are directions given to the compiler writers
about those types:

   A.4.4(106): 

                     Implementation Advice

   Bounded string objects should not be implemented by implicit
pointers and dynamic allocation.


   A.4.5(88):

                     Implementation Requirements

  No storage associated with an Unbounded_String object shall be lost
upon assignment or scope exit.

    Now if you are creating a type that needs special storage
management, my experience is that it requires about six lines.  If you
are creating something more ordinary, just use components of
predefined types like Unbounded_String, and don't worry about garbage
collection.

     Yes, it is possible to write code in Ada that leaks
memory absent garbage collection, but is well behaved if garbage
collection is provided, as it is by some implementations.  But such
programs are rare.  For the large majority of Ada programs, memory
management is not an issue.  (Or at least, it isn't an issue if there
ISN'T a garbage collector.)   For a much smaller set, but probably much
larger than the set where general garbage collection is helpful, you
do need to put in some storage management code.  But with Ada 95, the
most I have ever had to do was about one page of code.  (Create a type
descended from Controlled that cleans itself up when no longer visible
by calling Unchecked_Deallocation.  These objects are often used for
communication between tasks where a simple protected type won't
do. However, I'd say that 90% of such cases all you have to do is use
Unbounded_Strings.)

    I'll post a very useful example to comp.lang.ada soon.
--

					Robert I. Eachus

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