boost::bind在构造函数对象时,实参传递是采用传值方式的,中间会经过若干次的拷贝构造。对于不允许拷贝构造或拷贝构造性能开销较大的情形可以结合boost::ref增加一个wrapper层避免拷贝构造。下面是示例代码:
#include <iostream>
#include "boost/bind.hpp"
#include "boost/ref.hpp"
struct A
{
A(int aValue) : m_value(aValue)
{
std::cout << "A()" << std::endl;
}
A(const A& a)
{
std::cout << "A(const A&)" << std::endl;
this->m_value = a.m_value;
}
int m_value;
};
void f(A a)
{
std::cout << "f(A)" << std::endl;
}
void g(A& a)
{
std::cout << "g(A&)" << std::endl;
}
责任编辑:cyth