Trey Jackson wrote:
> Just started using boost::bind, like it a lot.
> I'm playing around with a little work crew,
> which just queues up data, then calls the function
> on them later.
[...]
> I'd like to be able to do something like:
> ,----------------
> | work_crew<???> mycrew(bind(&X::f, &x, _1, _2));
> |
> | mycrew.add( ?? 9 10 ?? );
> | mycrew.add( ?? 42 10 ?? );
> | mycrew.add( ?? 29232 10 ?? );
> |
> | // do work
> | mycrew.dowork(); // STILL calls x.f(9, 10), x.f(42,10),
> x.f(29232,10)b
> `----------------
>
>
> Where obviously I have to do something special to package up the
> arguments to the function object that's been created.
>
>
> Is it possible without a huge amount of coding?
I was doing something like it recently, so, sure:
#include "boost/function.hpp"
#include "boost/bind.hpp"
#include "boost/tuple/tuple.hpp"
#include "boost/tuple/apply.hpp"
#include <list>
using namespace boost;
template <class DataType, class FunctionType = boost::function1<void,
DataType> >
class work_crew {
std::list<DataType> queue_;
FunctionType engine_;
public:
work_crew(FunctionType const& tocall);
void add(DataType d) { queue_.push_front(d); };
void dowork()
{
typedef typename std::list<DataType>::iterator iterator_t;
for (iterator_t iter = queue_.begin(); iter != queue_.end(); ++iter)
tuples::apply(this->engine_, *iter); // here
};
};
struct X {
bool f(int a, int b);
};
X x;
int main()
{
work_crew< tuples::tuple<int,int>, boost::function2<void,int,int> >
mycrew(bind(&X::f, &x, _1, _2));
mycrew.add( tuples::make_tuple(9, 10) );
mycrew.add( tuples::make_tuple(42, 10) );
mycrew.add( tuples::make_tuple(29232, 10) );
// do work
mycrew.dowork(); // STILL calls x.f(9, 10), x.f(42,10), x.f(29232,10)b
}
With a little bit more of coding and Boost.MPL, you can do even better on
work_crew< tuples::tuple<int,int>, boost::function2<void,int,int> >
mycrew(bind(&X::f, &x, _1, _2));
line:
work_crew< mpl::list<int,int> > mycrew(bind(&X::f, &x, _1, _2));
but I am not sure if you want to dive into it from the beginning.
The only caveat to the above is that "tuple/apply.hpp" header is not a part
of the Boost yet. Please see
http://www.mail-archive.com/boost@lists.boost.org/msg05246.html for the
source.
We still have a chance to have the facility in 1.30 release, though (it's a
pure extension of Boost.Tuple library) - but I need to hear from Jaakko on
this one.
Aleksey
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