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From: kcline17@hotmail.com (Kevin Cline)
Newsgroups: comp.lang.ada
Subject: Re: worth the hassle?
Date: 22 Jul 2002 22:56:18 -0700
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"Frank J. Lhota" <NOSPAM.lhota.adarose@verizon.net> wrote in message news:<RYX_8.20976$927.2872@nwrddc01.gnilink.net>...
> "Stephen Leake" <stephen.a.leake.1@gsfc.nasa.gov> wrote in message
> news:uheirlk4z.fsf@gsfc.nasa.gov...
> > My own opinion is that supporting limited types is a requirement for
> > any general-purpose container.
> >
> > This is probably one reason why Ada will never be as popular as C++;
> > in C++, you don't have to make this kind of decision :).
> 
> Why isn't this a C++ issue as well? Certainly it is possible to declare the
> C++ equivalent of a limited type, i.e. a type for which assignment is not
> available.

It is a C++ issue, but it is now fairly standard practice to write
containers that only require the contained class to have a copy constructor.
The STL is implemented in this way.  The containers allocate raw memory,
and use placement-new and explicit destructor calls to create and
destroy objects, like this:

char* mem = new char[sizeof T];  // get some memory
T* t = new T(mem, *oldT); // copy-construct object on mem
t->~T();                  // destroy object

Not the sort of thing one would want to see sprinkled through
an application, but fine if encapsulated in a container class.