Re: [sigc] Accumulators

[Martin Schulze <martin-ml hippogriff de>]

You are right - this look like a bug!

Most likely, in signal.h.m4, definition of struct signal_emit$1, line:

  typedef internal::slot_iterator_buf<self_type> slot_iterator_buf_type;

should read:

  typedef internal::slot_iterator_buf<self_type,T_return>
slot_iterator_buf_type;

Could you file a bug report, please?

Thanks!

  Martin


Am Samstag, den 03.06.2006, 21:10 -0600 schrieb Timothy M. Shead:
> I'm using libsigc++ 2.0.16 on Gentoo Linux, and trying to write an
> accumulator for the first time, one that takes slots that return int and
> returns a std::vector<int>.  Unfortunately, I get a compile error - it
> seems that the iterators passed to the accumulator are picking-up on the
> accumulator result_type, instead of the slot result_type, leading to
> errors.  Does anyone have an example of an accumulator whose result type
> differs from the slot result_type?
> 
> Thanks in advance,
> Tim Shead
> 
> #include <sigc++/signal.h>
> #include <vector>
> 
> class accumulate
> {
> public:
>         typedef std::vector<int> result_type;
> 
>         template<typename IteratorT>
>         result_type operator()(IteratorT First, IteratorT Last)
>         {
>                 result_type result;
> 
>                 for(; First != Last; ++First)
>                         result.push_back(*First);
> 
>                 return result;
>         }
> };
> 
> int foo()
> {
>         return 1;
> }
> 
> int bar()
> {
>         return 2;
> }
> 
> int main(int argc, char* argv[])
> {
>         sigc::signal0<int, accumulate> signal;
> 
>         signal.connect(sigc::ptr_fun(foo));
>         signal.connect(sigc::ptr_fun(bar));
> 
>         std::vector<int> results = signal.emit();
> 
>         return 0;
> }
> 
> $ gcc -o test test.cpp -I/usr/include/sigc++-2.0 -I/usr/lib/sigc
> ++-2.0/include -lstdc++ -lsigc-2.0
> test.cpp: In member function `std::vector<int, std::allocator<int> > 
>    accumulate::operator()(IteratorT, IteratorT) [with IteratorT = 
>    sigc::internal::slot_iterator_buf<sigc::internal::signal_emit0<int, 
>    accumulate>, std::vector<int, std::allocator<int> > >]':
> /usr/include/sigc++-2.0/sigc++/signal.h:453:   instantiated from `static
> typename T_accumulator::result_type
> sigc::internal::signal_emit0<T_return,
> T_accumulator>::emit(sigc::internal::signal_impl*) [with T_return = int,
> T_accumulator = accumulate]'
> /usr/include/sigc++-2.0/sigc++/signal.h:1702:   instantiated from
> `typename sigc::internal::signal_emit0<T_return,
> T_accumulator>::result_type sigc::signal0<T_return,
> T_accumulator>::emit() const [with T_return = int, T_accumulator =
> accumulate]'
> test.cpp:38:   instantiated from here
> test.cpp:25: error: no matching function for call to `std::vector<int, 
>    std::allocator<int> >::push_back(std::vector<int, std::allocator<int>
> >)'
> /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/include/g
> ++-v3/bits/stl_vector.h:596: error: candidates
>    are: void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp =
> int, 
>    _Alloc = std::allocator<int>]
> /usr/include/sigc++-2.0/sigc++/signal.h: In member function `T_result 
>    sigc::internal::slot_iterator_buf<T_emitter, T_result>::operator*()
> const 
>    [with T_emitter = sigc::internal::signal_emit0<int, accumulate>,
> T_result = 
>    std::vector<int, std::allocator<int> >]':
> test.cpp:25:   instantiated from `std::vector<int, std::allocator<int> >
> accumulate::operator()(IteratorT, IteratorT) [with IteratorT =
> sigc::internal::slot_iterator_buf<sigc::internal::signal_emit0<int,
> accumulate>, std::vector<int, std::allocator<int> > >]'
> /usr/include/sigc++-2.0/sigc++/signal.h:453:   instantiated from `static
> typename T_accumulator::result_type
> sigc::internal::signal_emit0<T_return,
> T_accumulator>::emit(sigc::internal::signal_impl*) [with T_return = int,
> T_accumulator = accumulate]'
> /usr/include/sigc++-2.0/sigc++/signal.h:1702:   instantiated from
> `typename sigc::internal::signal_emit0<T_return,
> T_accumulator>::result_type sigc::signal0<T_return,
> T_accumulator>::emit() const [with T_return = int, T_accumulator =
> accumulate]'
> test.cpp:38:   instantiated from here
> /usr/include/sigc++-2.0/sigc++/signal.h:296: error: no match for
> 'operator=' in 
> 
> 'this->sigc::internal::slot_iterator_buf<sigc::internal::signal_emit0<int, 
>    accumulate>, std::vector<int, std::allocator<int> > >::r_ = 
> 
> this->sigc::internal::slot_iterator_buf<sigc::internal::signal_emit0<int, 
>    accumulate>, std::vector<int, std::allocator<int> > 
>    >::c_->sigc::internal::signal_emit0<T_return,
> T_accumulator>::operator() 
>    [with T_return = int, T_accumulator = 
>    accumulate]((+(&this->std::_List_iterator<_Tp, _Ref, _Ptr>::operator*
> [with 
>    _Tp = sigc::slot_base, _Ref = const sigc::slot_base&, _Ptr = const 
>    sigc::slot_base*]())))'
> /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/include/g
> ++-v3/bits/vector.tcc:128: error: candidates
>    are: std::vector<_Tp, _Alloc>& std::vector<_Tp,
> _Alloc>::operator=(const 
>    std::vector<_Tp, _Alloc>&) [with _Tp = int, _Alloc =
> std::allocator<int>]
> distcc[12622] ERROR: compile test.cpp on localhost failed
> 
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