libsigc++ 2.2.10
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Convenience wrapper for the numbered sigc::signal# templates. More...
#include <sigc++/signal.h>
Public Member Functions | |
accumulated (const accumulated& src) |
Convenience wrapper for the numbered sigc::signal# templates.
Like sigc::signal but the additional template parameter T_accumulator defines the accumulator type that should be used.
An accumulator is a functor that uses a pair of special iterators to step through a list of slots and calculate a return value from the results of the slot invokations. The iterators' operator*() executes the slot. The return value is buffered, so that in an expression like
a = (*i) * (*i);
the slot is executed only once. The accumulator must define its return value as result_type
.
struct arithmetic_mean_accumulator { typedef double result_type; template<typename T_iterator> result_type operator()(T_iterator first, T_iterator last) const { result_type value_ = 0; int n_ = 0; for (; first != last; ++first, ++n_) value_ += *first; return value_ / n_; } };
struct interruptable_accumulator { typedef bool result_type; template<typename T_iterator> result_type operator()(T_iterator first, T_iterator last) const { for (; first != last; ++first, ++n_) if (!*first) return false; return true; } };