Re: [Boost-users] using lambda as function argument.

From: chun ping wang (cablepuff_at_[hidden])
Date: 2006-04-19 12:59:40

so does anyone know how to fix previous error above?
On 4/15/06, chun ping wang <cablepuff_at_[hidden]> wrote:
>
> k ignore hte previous example..i figure out a way around that using
> BOOST_FOREACH....
>
> Operator- version 1 works.
>
> template <typename T,
>          template <typename ELEM, typename = std::allocator<ELEM> >
>          class CONT
> >
> CONT<T> operator-(CONT<T> arr1, CONT<T> arr2)
> {
>    using namespace boost::lambda;
>    typedef typename CONT<T>::size_type sz;
>    const sz arr1Size(arr1.size());
>    const sz arr2Size(arr2.size());
>    BOOST_STATIC_ASSERT(arr1Size == arr2Size);
>    std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(), _1
> -= _2);
>    return arr1;
> }
>
> operator version 2: does not work.
>
> template <typename T,
>          template <typename ELEM, typename = std::allocator<ELEM> >
>          class CONT
> >
> CONT<CONT<T> > operator-(CONT<CONT<T> > arr1, CONT<CONT<T> > arr2)
> {
>       using namespace boost::lambda;
>       std::transform(arr1.begin(), arr1.end(), arr2.begin(), arr1.end(),
>       protect(_1 - _2));
>       return arr1;
> }
>
> Heres hte error i get.
> 826 C:\Dev-Cpp\include\c++\3.4.2\bits\stl_algo.h no match for 'operator='
> in '(&__result)->__gnu_cxx::__normal_iterator<_Iterator,
> _Container>::operator* [with _Iterator = std::vector<long int,
> std::allocator<long int> >*, _Container = std::vector<std::vector<long int,
> std::allocator<long int> >, std::allocator<std::vector<long int,
> std::allocator<long int> > > >]() = boost::lambda::lambda_functor<Base>::operator()(A&,
> B&) const [with A = std::vector<long int, std::allocator<long int> >, B =
> std::vector<long int, std::allocator<long int> >, T = boost::lambda
> ::lambda_functor_base<boost::lambda::protect_action,
> boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda
> ::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::minus_action>,
> boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1>
> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >,
> 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> > >,
> 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,
> boost::tuples::null_type> >](((std::vector<long int, std::allocator<long
> int> >&)(+(&__first1)->__gnu_cxx::__normal_iterator<_Iterator,
> _Container>::operator* [with _Iterator = std::vector<long int,
> std::allocator<long int> >*, _Container = std::vector<std::vector<long int,
> std::allocator<long int> >, std::allocator<std::vector<long int,
> std::allocator<long int> > > >]())), ((std::vector<long int,
> std::allocator<long int>
> >&)(+(&__first2)->__gnu_cxx::__normal_iterator<_Iterator,
> _Container>::operator* [with _Iterator = std::vector<long int,
> std::allocator<long int> >*, _Container = std::vector<std::vector<long int,
> std::allocator<long int> >, std::allocator<std::vector<long int,
> std::allocator<long int> > > >]())))'
>
>  note C:\Dev-Cpp\include\c++\3.4.2\bits\vector.tcc:131 candidates are:
> std::vector<T, Allocator>& std::vector<T, Allocator>::operator=(const
> std::vector<T, Allocator>&) [with _Tp = long int, _Alloc =
> std::allocator<long int>]
>
> anyone care to explain how to fix these errors? Thanks.
>
>
> On 4/14/06, chun ping wang <cablepuff_at_[hidden]> wrote:
> >
> > For some reason this thing don't work. I want to print a container of
> > container.....
> >
> >
> >
> > #ifndef ARRAY_OPERATION_HPP
> > #define ARRAY_OPERATION_HPP
> > #include <iostream>
> > #include <boost/lambda/lambda.hpp>
> >
> > template <typename T,
> >          template <
> >                   typename ELEM,
> >                   typename = std::allocator<ELEM>
> >          >
> >          class CONT
> > >
> > void print_array(const CONT<T>& array)
> > {
> >      using namespace boost::lambda;
> >      std::for_each(array.begin(), array.end(), std::cout << _1 << " ");
> > }
> >
> > template <typename T,
> >          template <
> >                   typename ELEM,
> >                   typename = std::allocator<ELEM>
> >          >
> >          class CONT
> > >
> > void print_2darray (const CONT<CONT<T> >& array)
> > {
> >      using namespace boost::lambda;
> >         CONT<T> temp;
> >         std::for_each(array.begin(), array.end(),
> >               bind<T, CONT>(print_array<T, CONT>(), _1)
> >         );
> > }
> >
> > #endif /* ARRAY_OPERATION_HPP */
> >
> > if i have std::list<std::list<double> > lOflDouble
> >
> > // insert some value in here.
> >
> > print_2darray<double>(lOflDouble);
> >
> > /*
> > 30 C:\cs classes\cs540\c++\ContainerOperation.hpp no matching function
> > for call to `print_array()'
> > */
> >
> >
> > On 4/14/06, David Abrahams < dave_at_[hidden]> wrote:
> > >
> > > "chun ping wang" <cablepuff_at_[hidden]> writes:
> > >
> > > > Heres a simple question, that i want to do.
> > > >
> > > > Lets say you have a function call void f(double);
> > > >
> > > > and then you want to apply f to each argument inside vector<double>
> > > a;
> > > >
> > > >  for_each(a.begin(), a.end(), f(_1));
> > > >
> > > > // the example above isn't possible..is there a simple way to do
> > > > this?
> > >
> > >   for_each(a.begin(), a.end(), bind(f, _1));
> > >
> > > HTH,
> > >
> > > --
> > > Dave Abrahams
> > > Boost Consulting
> > > www.boost-consulting.com
> > >
> > > _______________________________________________
> > > Boost-users mailing list
> > > Boost-users_at_[hidden]
> > > http://lists.boost.org/mailman/listinfo.cgi/boost-users
> > >
> >
> >
>