Re: Using assignment operator when rhs is temporary object.

From:

Ulrich Eckhardt <eckhardt@satorlaser.com>

Newsgroups:

microsoft.public.vc.language

Date:

Mon, 05 Oct 2009 17:29:39 +0200

Message-ID:

<30gpp6-cab.ln1@satorlaser.homedns.org>

Vladimir Grigoriev wrote:

I have seen that I may not do the following with std::auto_ptr

const std::auto_ptr<int> & f()
{
    static std::auto_ptr<int> ai( new int( 10 ) );
    return ( ai );
}

main()
{
    const std::auto_ptr<int> ai = f();
}

Yes, and? auto_ptr is designed to give exclusive ownership, i.e. that only a
single auto_ptr instance ever has ownership of the pointee. Depending on
how you would like said code to be interpreted, either you would end up
with two auto_ptrs pointing at the same pointee or with an auto_ptr being
modified through a reference-to-const-auto_ptr.

Note: Just in case you want the pointee instead of the pointer to become
const, you need an auto_ptr<int const>.

  int* <~> auto_ptr<int>
  int const* <~> auto_ptr<int const>
  int* const <~> auto_ptr<int> const

Uli

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