Re: Is it possible to catch an exception raised by a member variable?

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Fri, 28 Sep 2007 10:35:27 -0400
Message-ID:
<fdj3fe$c6p$1@news.datemas.de>
Chris ( Val ) wrote:

On Sep 28, 10:52 pm, Pete Becker <p...@versatilecoding.com> wrote:

On 2007-09-28 05:30:31 -0400, "Chris ( Val )" <chris...@gmail.com>
said:

int main()
 {
  Base* B;

  try {
   B = new Base( "Oracle.driver.bar" );
  }
 catch( const std::exception& e )
  {
   B->Print();
   delete B;
  }

  std::cin.get();
  return 0;
 }

I am interested to hear your, and the groups
thoughts on the validity of such a construct.


It really doesn't show anything. Replace the "B = new ..." with
"throw std::exception();" and you'll probably get the same result.
Calling member functions on uninitialized pointers produces
undefined behavior, so anything you see is as valid as anything else.


I tried a non pointer version, and the results are the same.

What I am curious about is at what point does the object actually
cease to exist? (which scope?)


The pointer does not cease to exist. The object, however, is not
created. So, whatever address the pointer contains in the 'catch'
block, is not the address of a valid object. That makes the pointer
_invalid_.

Is it not possible for it to even be partially constucted to
report such information back?


Partially constructed means not fully constructed, doesn't it? In
my book you cannot use any partially constructed object except to
take its address.

I know UB can mean anything can happen, but I'm curious.
Its a powerful drug that UB, it can get you hooked line
and sinker :-)


Yep.

V
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