On 12/06/2012 06:34 AM, Chris Stankevitz wrote:

Hello,

Below I implement a function "Chain" that takes two functions and executes them both.

The first approach succeeds: direct function call.

The second approach succeeds: call via bind with explicit template arguments

The third and fourth approaches fail: call via bind without explicit template arguments (with/without boost::protect)

Question: Why do I have to use explicit template arguments when using bind with Chain? Chain is a template function. Its address isn't known until it gets instantiated. In order to bind a function, bind needs to know the address (aka which function to bind to). This means, that you have to specify the complete type.

Thank you,

Chris

===

#include<boost/bind.hpp> #include<boost/function.hpp>

template<typename TAFunc1, typename TAFunc2> void Chain(const TAFunc1& Func1, TAFunc2& Func2) { Func1(); Func2(); }

void f() { }

void foo() { boost::function<void()> x = boost::bind(f);

boost::function<void()> y = boost::bind(f);

Chain(x, y);

boost::bind(Chain<boost::function<void()>, boost::function<void()> >, x, y)();

boost::bind(Chain, x, y)();

boost::bind(Chain, boost::protect(x), boost::protect(y))(); } _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

On Wed, Dec 5, 2012 at 9:34 PM, Chris Stankevitz <chrisstankevitz@gmail.com> wrote:

template <typename TAFunc1, typename TAFunc2> void Chain(const TAFunc1& Func1, TAFunc2& Func2) { Func1(); Func2(); }

Another problem with this: The second argument should be a const reference, not a mutable reference. Chris