Re: [boost] Re: In-place construction for variant

From: E. Gladyshev (egladysh_at_[hidden])
Date: 2003-11-04 14:52:40

--- David Abrahams <dave_at_[hidden]> wrote:
[...]
> If your system gives you cause to worry about catch(...), it's much
> simpler to use the destructors of automatic objects than to define
> such a complicated mechanism for recovery.

Of course you should worry about catch(...) on any real system.
Also our programs are most likely not correct.

Using destructors is a completely different approach to 
exception handling.  If it is safer in practice, then
we should talk about it.  It'll have huge consequences
on how "industry-strength" libraries is supposed to
be written.

> 
> > So the claim that "Interactions between templates and exceptions are
> > not well-understood." might after all be true in opposite to what
> > your article is suggesting.
> 
> Just as the article suggests, these issues are exactly the same ones
> that arise with library functions which accept function pointers or
> (runtime) polymorphic objects.  There's no particular mysterious
> interaction with templates.
> 
> And this is my last post in this thread.  I hope it helped,

Yes, this discussion is really helped. Thanks to all!

Here is my last point.

My concern is that boost is a very respectable
site and community, so most people will look at your article
that has the following code:

template <class X> 
void print_random_sequence() 
{ 
    std::vector<X> v(10); // A vector of 10 items 
    try { 
        // Provides only the basic guarantee 
        v.insert( v.begin(), X() ); 
    } 
    catch(...) {} // ignore any exceptions above 
    // print the vector's contents 
    std::cout "(" << v.size() << ") "; 
    std::copy( v.begin(), v.end(), 
    std::ostream_iterator<X>( std::cout, " " ) ); 
} 

and assume that it is safe to use this approach in their programs
and that they are covered from trouble. It is really really dangerous.

I suggest for you to at least elaborate in your article on some
of the issues that have been discussed in this thread.

Eugene

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