Re: [Boost-users] bosst::bind problem

28 Jul 2005

      On 7/28/05, Oleg Smolsky  wrote:
...
Hi all,
I've just started using boost::bind and found the following problem:
class Handler
{
public:
    bool Test1(std::string sComponent);
    bool Test2(std::string sComponent, std::string sAddress);
};
void Test()
{
    std::vector<Handler>    v;
// This compiles
    std::string             a, b;
    std::for_each(v.begin(), v.end(),
                  boost::bind(&Handler::Test1, _1, a));
// This doesn't compile
    //std::for_each(v.begin(), v.end(),
    //              boost::bind(&Handler::Test2, _1, _2, a, b));
}
Environment: boost 1.32, VC8, WinXP.
Any ideas?
Thanks,
Oleg.
Oleg - the _1 and _2 represent the parameter(s) passed *to* the
boost::bind function by the caller (in this case std::for_each, which
passes a Handler object instance). Now, std::for_each only passes one
argument, so there can't be a _2 here.

What you want for the second one is:

boost::bind(&Handler::Test2, _1, a, b)

The main thing to remember is that boost::bind makes explicit the
implicit extra argument to object methods (the object instance, or
'this').

HTH
Stuart Dootson