Re: [Boost-users] ptr_container: ptr_map.insert() not compiling?

Thorsten Ottosen wrote:

Duane Murphy wrote:

...

I'm trying to use boost::ptr_map<> and cannot get calls insert to compile.

I'm on Mac OS X using gcc 3.3 with Xcode.

Even the most basic code fails to compile:

boost::ptr_map< in, int* > my_map; int * val = new int( 22 ); my_map.insert( 1, val );

See http://www.boost.org/libs/ptr_container/doc/ptr_map_adapter.html

The first argument needs to be a reference:

int key = 1; my_map.insert( key, new int(22) );

1.34 adds the followinf overload:

template< class U > std::pair insert( const key_type& key, std::auto_ptr<U> x )

which does allow the key to be an rvalue (just don't create the auto_ptr in the function call).

Thorsten, I've suggested this before: http://article.gmane.org/gmane.comp.lib.boost.devel/132706/match=re+ptr+cont... but I'll try again. Taking the key by reference guarantees nothing except confused users. A more sane way to solve this would be to delay possible implicit conversions until after the pointer has been protected: template std::pair insert(K const& k, U* p) { std::auto_ptr<U> owned(p); this->insert(implicit_cast(k), owned); } -- Daniel Wallin Boost Consulting www.boost-consulting.com