Re: Some problems with std::vector and nested templates
jubelbrus wrote:
Sorry about the misspellings...
This is what I'm trying to do:
Write a template class that stores a list of boost::shared_ptr<T> with
a index and is thread safe, where T would be that template <class T>
stuff..
I got the getitem function compiling by using typename, tanks.. but
I've discovered some compile problems with my insert code.
#include <stdint.h>
#include <vector>
#include <boost/thread/mutex.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/tuple/tuple.hpp>
template <class T>
class list{
boost::mutex m_lock;
std::vector<boost::tuple<uint32_t, boost::shared_ptr<T> > >
m_vector;
uint32_t m_nextid;
uint32_t insert(boost::shared_ptr<T>);
}
template <class T>
uint32_t list<T>::insert(boost::shared_ptr<T>)
{
typename boost::tuples::tuple<uint32_t, boost::shared_ptr<T> >
add_item(m_nextid, item);
There should be no typename here.
typename std::vector<boost::tuple<uint32_t, boost::shared_ptr<T> >
m_vector;
nor here.
typename are needed in:
T::something
or
someclass<T>::something
To put it very short.
This is because the compiler cannot possibly know what something is. The
first is obvious. The second:
template <class T>
class someclass {
public:
typedef T something;
};
int p;
template <class T>
void foo() {
someclass<T>::something * p; /*Missing typename and definition of local p
or multiplication? Standard says multiplication */
}
template <>
class someclass<int> {
public:
int something;
};
int someclass<int>::something = 3;
int main() {
p = 42;
foo<int>();
}
boost::mutex::scoped_lock lock(m_lock);
m_vector.insert( add_item );
return m_nextid++;
};
I get the following error:
list.h: In member function 'uint32_t
stdtools::list<T>::insert(boost::shared_ptr<T>) [with T = int]':
tester_a.cpp:10: instantiated from here
list.h:90: error: no matching function for call to
// beginning
'std::vector<boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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>,
std::allocator<boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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> >
::insert(boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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>&)'
//end
Shorter:
std::vector<...>::insert(tuple<...>)
/usr/include/c++/4.0.0/bits/vector.tcc:93: note: candidates are:
//beginning
typename std::vector<_Tp, _Alloc>::iterator std::vector<_Tp,
_Alloc>::insert(__gnu_cxx::__normal_iterator<typename _Alloc::pointer,
std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp =
boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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>, _Alloc =
std::allocator<boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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> >]
//end
shorter:
std::vector<...>::insert(std::vector<...>::iterator, const tuple<...>&)
/usr/include/c++/4.0.0/bits/stl_vector.h:657: note:
void std::vector<_Tp,
//beginning
_Alloc>::insert(__gnu_cxx::__normal_iterator<typename _Alloc::pointer,
std::vector<_Tp, _Alloc> >, size_t, const _Tp&) [with _Tp =
boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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>, _Alloc =
std::allocator<boost::tuples::tuple<uint32_t, boost::shared_ptr<int>,
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> >]
//end
shorter:
std::vector<...>::insert(std::vector<...>::iterator, size_t, const
tuple<...>&)
Read the messages. They're long and hairy, but it's possible. Matching
parens is a good start.
--
rbh