Hello,
I'm new to the Boost library and quite excited to see some of the
tools available to assist writing functional-style code.
Recently I wanted to perform an action on every object in a container
of smart pointers (boost::shared_ptr). I couldn't seem to find a
concise way to do so. Here is a small example (no container involved)
demonstrating the problem I'm encountering.
#include <iostream>
#include <string>
#include
#include
using namespace std;
using namespace boost;
void
xprint(ostream *os, shared_ptr<string> p)
{
*os << p.get()->c_str() << endl;
}
void
xprint2(ostream *os, string *p)
{
*os << p->c_str() << endl;
}
int
main(int ac, char *av[])
{
shared_ptr<string> p(new string("Test"));
bind(xprint, &cerr, _1)(p);
#ifdef THIS_DOES_NOT_WORK
bind(xprint2, &cerr, _1)(
bind(&shared_ptr<string>::get, _1)(p)
);
#else
string *q = bind(&shared_ptr<string>::get, _1)(p);
bind(xprint2, &cerr, _1)(q);
#endif
return 0;
}
Using GCC 3.2, I encounter a `no match for call' error in the
`THIS_DOES_NOT_WORK' section of code. (Full diagnostics below.) I
have tried many variations using mem_fn, apply, and by specifying the
return type of the functor explicitly, but with no success.
I'm afraid I don't understand the problem. I hoped someone here might
be able to hit me with a clue-stick :-)
Cheers,
--
Jacques Vidrine . NTT/Verio SME . FreeBSD UNIX . Heimdal
nectar@celabo.org . jvidrine@verio.net . nectar@freebsd.org . nectar@kth.se
g++ -DTHIS_DOES_NOT_WORK -I/usr/local/include example.cc
example.cc: In function `int main(int, char**)':
example.cc:31: no match for call to `(boost::_bi::bind_tstd::ostream*, boost::arg<1> > >) (
std::string*)'
/usr/local/include/boost/bind/bind_template.hpp:19: candidates are:
boost::_bi::result_traits::type boost::_bi::bind_t::operator()() [with R = void, F = void (*)(std::ostream*, std::string*),
L = boost::_bi::list2std::ostream*, boost::arg<1> >]
/usr/local/include/boost/bind/bind_template.hpp:25:
boost::_bi::result_traits::type boost::_bi::bind_t::operator()() const [with R = void, F = void (*)(std::ostream*,
std::string*), L = boost::_bi::list2std::ostream*,
boost::arg<1> >]
/usr/local/include/boost/bind/bind_template.hpp:31:
boost::_bi::result_traits::type boost::_bi::bind_t::operator()(A1&) [with A1 = std::string*, R = void, F = void
(*)(std::ostream*, std::string*), L =
boost::_bi::list2std::ostream*, boost::arg<1> >]
/usr/local/include/boost/bind/bind_template.hpp:37:
boost::_bi::result_traits::type boost::_bi::bind_t::operator()(A1&) const [with A1 = std::string*, R = void, F = void
(*)(std::ostream*, std::string*), L =
boost::_bi::list2std::ostream*, boost::arg<1> >]
