BOOST_FOREACH在模板内不起作用
BOOST_FOREACH does not work inside template?
我试图在一个带有自定义但与类型参数无关的迭代器的模板函数中使用BOOST_FOREACH。我得到4-5个错误,这表明我的迭代器类没有很好地定义为迭代器。
在没有BOOST_FOREACH的情况下重写循环,或者"取消模板化"函数,可以消除错误。
这是BOOST_FOREACH的已知限制吗?
编辑
对不起。部分代码:
template <class T>
T fun()
{
T result(0.0);
BOOST_FOREACH(const math::IntegerVector &v, math::IntegerVectorRange(math::IntegerVector(2 , 2 ,2)))
{
// Do stuff.
}
return result;
}
IntegrVector*类型定义良好,在模板之外运行良好。此外,它们不依赖于T.
完整的错误是:
make[1]: Entering directory `/home/panayk/Workspace/petros-game'
Making all in src/c++
make[2]: Entering directory `/home/panayk/Workspace/petros-game/src/c++'
depbase=`echo fluid/Tracer.lo | sed 's|[^/]*$|.deps/&|;s|.lo$||'`;
/bin/bash ../../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -I../.. -I/usr/include/python2.7 -I/usr/include -O2 -I/usr/include/python2.7 -MT fluid/Tracer.lo -MD -MP -MF $depbase.Tpo -c -o fluid/Tracer.lo fluid/Tracer.cc &&
mv -f $depbase.Tpo $depbase.Plo
libtool: compile: g++ -DHAVE_CONFIG_H -I. -I../.. -I/usr/include/python2.7 -I/usr/include -O2 -I/usr/include/python2.7 -MT fluid/Tracer.lo -MD -MP -MF fluid/.deps/Tracer.Tpo -c fluid/Tracer.cc -fPIC -DPIC -o fluid/.libs/Tracer.o
In file included from /usr/include/boost/iterator/iterator_categories.hpp:15:0,
from /usr/include/boost/iterator/detail/facade_iterator_category.hpp:7,
from /usr/include/boost/iterator/iterator_facade.hpp:14,
from ./math/Vector.h:5,
from ./fluid/Tracer.h:4,
from fluid/Tracer.cc:1:
/usr/include/boost/mpl/eval_if.hpp: In instantiation of 'boost::mpl::eval_if<mpl_::bool_<false>, boost::range_const_iterator<math::IntegerVectorRange>, boost::range_mutable_iterator<math::IntegerVectorRange> >':
/usr/include/boost/foreach.hpp:364:13: instantiated from 'boost::foreach_detail_::foreach_iterator<math::IntegerVectorRange, mpl_::bool_<false> >'
make[2]: Leaving directory `/home/panayk/Workspace/petros-game/src/c++'
./fluid/InterpolatorGrid.h:45:3: instantiated from here
make[1]: Leaving directory `/home/panayk/Workspace/petros-game'
/usr/include/boost/mpl/eval_if.hpp:38:31: error: no type named 'type' in 'boost::mpl::eval_if<mpl_::bool_<false>, boost::range_const_iterator<math::IntegerVectorRange>, boost::range_mutable_iterator<math::IntegerVectorRange> >::f_ {aka struct boost::range_mutable_iterator<math::IntegerVectorRange>}'
In file included from fluid/Tracer.cc:3:0:
./fluid/InterpolatorGrid.h: In member function 'T fluid::InterpolatorGrid::interpolate(const std::vector<std::vector<std::vector<T> > >&, const RealVector&) const':
./fluid/InterpolatorGrid.h:45:3: error: no matching function for call to 'begin(const boost::foreach_detail_::auto_any_base&, boost::foreach_detail_::type2type<math::IntegerVectorRange, mpl_::bool_<false> >*, boost::enable_if_c<true, boost::mpl::and_<boost::mpl::not_<boost::foreach::is_noncopyable<math::IntegerVectorRange> >, boost::foreach::is_lightweight_proxy<math::IntegerVectorRange>, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> > >::type*&)'
./fluid/InterpolatorGrid.h:45:3: note: candidates are:
/usr/include/boost/foreach.hpp:657:1: note: template<class T, class C> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, C>::type> boost::foreach_detail_::begin(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, C>*, mpl_::true_*)
/usr/include/boost/foreach.hpp:665:1: note: template<class T, class C> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, C>::type> boost::foreach_detail_::begin(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, C>*, mpl_::false_*)
/usr/include/boost/foreach.hpp:676:1: note: template<class T> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, mpl_::bool_<true> >::type> boost::foreach_detail_::begin(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, mpl_::bool_<true> >*, bool*)
/usr/include/boost/foreach.hpp:686:1: note: template<class T, class C> boost::foreach_detail_::auto_any<T*> boost::foreach_detail_::begin(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T*, C>*, mpl_::true_*)
./fluid/InterpolatorGrid.h:45:3: error: no matching function for call to 'end(const boost::foreach_detail_::auto_any_base&, boost::foreach_detail_::type2type<math::IntegerVectorRange, mpl_::bool_<false> >*, boost::enable_if_c<true, boost::mpl::and_<boost::mpl::not_<boost::foreach::is_noncopyable<math::IntegerVectorRange> >, boost::foreach::is_lightweight_proxy<math::IntegerVectorRange>, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> > >::type*&)'
./fluid/InterpolatorGrid.h:45:3: note: candidates are:
/usr/include/boost/foreach.hpp:697:1: note: template<class T, class C> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, C>::type> boost::foreach_detail_::end(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, C>*, mpl_::true_*)
/usr/include/boost/foreach.hpp:705:1: note: template<class T, class C> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, C>::type> boost::foreach_detail_::end(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, C>*, mpl_::false_*)
/usr/include/boost/foreach.hpp:716:1: note: template<class T> boost::foreach_detail_::auto_any<typename boost::foreach_detail_::foreach_iterator<T, mpl_::bool_<true> >::type> boost::foreach_detail_::end(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, mpl_::bool_<true> >*, bool*)
/usr/include/boost/foreach.hpp:726:1: note: template<class T, class C> boost::foreach_detail_::auto_any<int> boost::foreach_detail_::end(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T*, C>*, mpl_::true_*)
./fluid/InterpolatorGrid.h:45:3: error: no matching function for call to 'deref(const boost::foreach_detail_::auto_any_base&, boost::foreach_detail_::type2type<math::IntegerVectorRange, mpl_::bool_<false> >*)'
./fluid/InterpolatorGrid.h:45:3: note: candidate is:
/usr/include/boost/foreach.hpp:765:1: note: template<class T, class C> typename boost::foreach_detail_::foreach_reference::type boost::foreach_detail_::deref(boost::foreach_detail_::auto_any_t, boost::foreach_detail_::type2type<T, C>*)
make[2]: *** [fluid/Tracer.lo] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
等等。这太多了,我无法解读,但IntegerVectorRange::begin()在那里,并返回一个const_iterator。IntegrVectorRange::end()也是如此。
EDIT2(IntegrVectorRange内容)
class IntegerVectorIterator
: public boost::iterator_facade
<
IntegerVectorIterator,
const IntegerVector,
boost::forward_traversal_tag
>
{
private:
IntegerVector current;
const IntegerVector start, limit;
void increment();
bool equal(const IntegerVectorIterator& other) const;
const IntegerVector &dereference() const;
public:
IntegerVectorIterator(const IntegerVector &start,
const IntegerVector &limit);
IntegerVectorIterator(const IntegerVector ¤t,
const IntegerVector &start,
const IntegerVector &limit);
friend class boost::iterator_core_access;
};
class IntegerVectorRange
{
private:
const IntegerVector start, limit;
const IntegerVectorIterator end_it;
public:
IntegerVectorRange(IntegerVector limit);
IntegerVectorRange(IntegerVector start, IntegerVector limit);
typedef IntegerVectorIterator const_iterator;
const_iterator begin() const;
const const_iterator &end() const;
};
对缺失的类进行Dummy处理,GCC不喜欢:http://ideone.com/3O3OB.Clang++编译得很好。所以,我猜你有一个编译器错误,或者boost/foreach.hpp
中所有的#ifdefs
中都有一个错误
特别能说明问题的是实例化回溯的这一部分:
eval_if<bool_<false>, range_const_iterator<...>, range_mutable_iterator<...> >
这表明无论BOOST_FOREACH
使用什么机制来确定您是可变迭代还是常量迭代,这次都得到了错误的答案。
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