[boost] [Bind] How do I get bind to deduce the return type of for_each?

Subject: [boost] [Bind] How do I get bind to deduce the return type of for_each?
From: Thomas Jordan (thomasjordan_at_[hidden])
Date: 2010-04-14 15:13:08

Hi, 
I have been trying to use Boost.bind to create an 'STL algorithm function object' to pass into another, 'higher order,' STL algorithm (e.g., to pass a for_each into a for_each). However, I am struggling to get bind to deduce the correct return type of the for_each function object.  I include the relevant bits of the code below.

class myClass
{
public:
   int func(){return mValue;}
private:
   int mValue;
};

//wrapper for STL for_each
struct myForEach
{
   template <typename II, typename F> 
   F operator()(II begin, II end, F function) const
   {
      return std::for_each(begin, end, function);
   }
};

typedef vector<myClass> vocType;
typedef vector<vocType> vovType;

//overloaded member functions vocType::begin & end
typedef vocType::iterator (vocType::*fnPtr)();
typedef const vocType::iterator (vocType::*constFnPtr)() const;

vovType vov(10, vocType(10, myClass()));

main()
{
   for_each(vov.begin(), vov.end(),
        bind< ? >(myForEach(),   
                bind(static_cast<fnPtr>(&vocType::begin),_1),  
                bind(static_cast<fnPtr>(&vocType::end),_1),
                protect(bind(&myClass::func, _1)))
} 

I tried various things for bind<?>, but was only able to get the code to compile (eventually) on my Unix box when I substituted 
bind< boost::_bi::protected_bind_t<boost::_bi::bind_t<int, boost::_mfi::mf0<int, myClass>, boost::_bi::list1<boost::arg<1> (*)()> > > > for 
the bind<?>.  I had guessed this might work from studying the compiler error messages.  Obviously, this is not an ideal solution!

Also, I only used the myForEach wrapper after having first attempted - and similarly failed - to bind the raw STL for_each.

Is there any way I can help bind to deduce the correct return type - for either myForEach or std::for_each, or both?

WIth Best Regards,
Tom Jordan (Software Engineer)