[Boost-users] Using lambda bind as destruct functor to shared_ptr

From: Scott French (scott_at_[hidden])
Date: 2007-07-01 22:02:47

Hello,

Should the following code sample work? It is the simplest reproduction  
case I
could come up with:

#include <boost/lambda/lambda.hpp>
#include <boost/lambda/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <stdlib.h>

using namespace std;
using namespace boost;
using namespace boost::lambda;

int main(void)
{
     void * myResource = malloc(5);
     shared_ptr<void> mySharedResource(myResource, bind(free, _1));
}

I get a compile error using g++ 4.0.1 on Mac OS X:

/Documents/boost_1_34_0/boost/detail/sp_counted_impl.hpp: In member  
function
'void* boost::detail::sp_counted_impl_pd<P, D>::get_deleter(const
std::type_info&) [with P = void*, D =
boost::lambda::lambda_functor<boost::lambda:: 
lambda_functor_base<boost::lambda::
action<2,
boost::lambda::function_action<2, void> >, boost::tuples::tuple<void  
(&)(void*),
const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
boost::tuples::null_type, boost::tuples::null_type,  
boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,  
boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> > >]':
test.cpp:13:   instantiated from here
/Documents/boost_1_34_0/boost/detail/sp_counted_impl.hpp:150: error: no  
match
for ternary 'operator?:' in '(+ ti)->std::type_info::operator==(((const
std::type_info&)((const std::type_info*)(&
_ZTIN5boost6lambda14lambda_functorINS0_19lambda_functor_baseINS0_6action 
ILi2ENS0
_15function_actionILi2EvEEEENS_6tuples5tupleIRFvPvEKNS1_INS0_11placehold 
erILi1EE
EEENS7_9null_typeESG_SG_SG_SG_SG_SG_SG_EEEEEE))))
? boost::lambda::operator&(const boost::lambda::lambda_functor<T>&)  
[with Arg =
boost::lambda::lambda_functor_base<boost::lambda::action<2,
boost::lambda::function_action<2, void> >, boost::tuples::tuple<void  
(&)(void*),
const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >,
boost::tuples::null_type, boost::tuples::null_type,  
boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type,  
boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type> >]() : 0'

Of course, just using "free" instead of bind(free, _1) works, but my  
real case
is more complicated and this appears to be a general conflict between
lambda::bind and shared_ptr.

Thanks,
Scott French