Re: [Boost-users] ptr_map bug in 1.33.1

From: Thorsten Ottosen (tottosen_at_[hidden])
Date: 2006-03-05 19:05:30

 > Hi, all,
 >
 > I'm a fresh hand to boost. I encounter some problems with ptr_map, in 
boost/ptr_container/detail/associative_ptr_container.hpp, line 107 & 111.
 >
 > size_type erase( const key_type& x ) // nothrow
 > {
 >   BOOST_ASSERT( !this->empty() );         iterator i = find( x ); 
                  // nothrow   // line 107
 >   if( i == this->end() )                      // nothrow
 >       return 0;                               // nothrow
 >   this->remove( i );                          // nothrow
 >   return this->c_private().erase( i.base() ); // nothrow   // line 111
 > }

This is a known bug that is fixed in the cvs.

 > Another thing for ptr_map_adapter is one of its Insert() overloads
 >
 > std::pair<iterator,bool> insert( key_type& key, value_type x )
 >
 > I wonder why we don't use const key_type&? Without const modifier, 
the compiler would not allow passing constants to it.

That is an exception-safety issue: if const key_type& was
accepted, it could create a leak.

In 1.34 you get a few other choices:

std::auto_ptr<T> p( new T("arg1","arg2") );
map.insert( "key", p );

boost::assign::ptr_map_insert( map )( "key", "arg1", "arg2" );

 > At last, never forget to mention my environment: VC 8.0
 > No test has been done in other environment.

Please also check that the bug still exists in the cvs:

http://www.boost.org/more/getting_started.html#CVS

Thanks

-Thorsten