升压未定义的引用误差的boost ::绑定重载运算

Question

有问题的代码：

boost::function<bool()> isSpecialWeapon = boost::bind(&WeaponBase::GetType,this) == WeaponType::SPECIAL_WEAPON; 

我得到的错误是像这样：

undefined reference to `boost::_bi::bind_t<bool, boost::_bi::equal, 
boost::_bi::list2<boost::_bi::bind_t<WeaponType::Guns, 
boost::_mfi::cmf0<WeaponType::Guns, WeaponBase>, 
boost::_bi::list1<boost::_bi::value<WeaponBase*> > >, 
boost::_bi::add_value<WeaponType::Guns>::type> > boost::_bi::operator== 
<WeaponType::Guns, boost::_mfi::cmf0<WeaponType::Guns, WeaponBase>, 
boost::_bi::list1<boost::_bi::value<WeaponBase*> >, WeaponType::Guns> 
(boost::_bi::bind_t<WeaponType::Guns, boost::_mfi::cmf0<WeaponType::Guns, WeaponBase>, 
boost::_bi::list1<boost::_bi::value<WeaponBase*> > > const&, WeaponType::Guns)' 

Answer 1

如果你不能得到boost::bind到按照您的愿望工作，您可以尝试Boost.Pheonix或Boost.Lamda作为解决方法。

尝试使用boost::pheonix::bind（从Boost.Pheonix），而不是boost::bind：

#include <boost/phoenix/operator.hpp> 
#include <boost/phoenix/bind/bind_member_function.hpp> 
#include <boost/function.hpp> 
#include <iostream> 

enum WeaponType {melee, ranged, special}; 

class Sword 
{ 
public: 
    WeaponType GetType() const {return melee;} 

    void test() 
    { 
     namespace bp = boost::phoenix; 
     boost::function<bool()> isSpecialWeapon = 
      bp::bind(&Sword::GetType, this) == special; 
     std::cout << "isSpecialWeapon() = " << isSpecialWeapon() << "\n"; 
    } 

}; 

int main() 
{ 
    Sword sword; 
    sword.test(); 
} 

---

另外，您还可以使用boost::lambda::bind（从Boost.Lambda）：

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

enum WeaponType {melee, ranged, special}; 

class Sword 
{ 
public: 
    WeaponType GetType() const {return melee;} 

    void test() 
    { 
     boost::function<bool()> isSpecialWeapon = 
      boost::lambda::bind(&Sword::GetType, this) == special; 
     std::cout << "isSpecialWeapon() = " << isSpecialWeapon() << "\n"; 
    } 

}; 

int main() 
{ 
    Sword sword; 
    sword.test(); 
}