本文介绍了为什么的boost ::绑定向前声明不兼容?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
的boost ::绑定
无法绑定通过正向声明中声明的参数。
boost::bind
is unable to bind parameters declared via a forward declaration.
任何人能解释为什么吗?这是一个提升的bug?
Can anyone explain why? Is this a boost bug?
样code:
#include "boost/function.hpp"
#include "boost/bind.hpp"
#include <vector>
#include <iostream>
class B;
class A
{
public:
A() {}
void func1(int i) { std::cout << __PRETTY_FUNCTION__ << "(" << i << ")\n"; }
void func2(const std::string& s) { std::cout << __PRETTY_FUNCTION__ << "(" << s << ")\n"; }
void func3(const B& b) { std::cout << __PRETTY_FUNCTION__ << "(" << "unknown" << ")\n"; }
static void dispatch( std::vector<A>& vect, boost::function<void(A &)> const& func)
{
for ( std::vector<A>::iterator iter = vect.begin();
iter != vect.end();
++iter )
{
func(*iter);
}
}
};
int main()
{
std::vector<A> vect(3);
A::dispatch(vect, boost::bind(&A::func1, _1, 3));
A::dispatch(vect, boost::bind(&A::func2, _1, "hello"));
const B* b = NULL;
A a;
a.func3( *b ); // compiles and works!!
A::dispatch(vect, boost::bind(&A::func3, _1, *b)); // does not compile!!
}
报告的错误是:
main.cpp:37:52: error: invalid use of incomplete type 'class B'
A::dispatch(vect, boost::bind(&A::func3, _1, *b)); // does not compile
现场演示:
#include "boost/function.hpp"
#include "boost/bind.hpp"
#include <vector>
#include <iostream>
class B;
class A
{
public:
A() {}
void func1(int i) { std::cout << __PRETTY_FUNCTION__ << "(" << i << ")\n"; }
void func2(const std::string& s) { std::cout << __PRETTY_FUNCTION__ << "(" << s << ")\n"; }
void func3(const B& b) { std::cout << __PRETTY_FUNCTION__ << "(" << "unknown" << ")\n"; }
static void dispatch( std::vector<A>& vect, boost::function<void(A &)> const& func)
{
for ( std::vector<A>::iterator iter = vect.begin();
iter != vect.end();
++iter )
{
func(*iter);
}
}
};
int main()
{
std::vector<A> vect(3);
A::dispatch(vect, boost::bind(&A::func1, _1, 3));
A::dispatch(vect, boost::bind(&A::func2, _1, "hello"));
const B* b = NULL;
A a;
a.func3( *b ); // compiles and works!!
A::dispatch(vect, boost::bind(&A::func3, _1, boost::cref(*b)));
}
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