使用std :: bind2nd和引用 [英] Using std::bind2nd with references
问题描述
我有一个类似这样的简单类:
I have a simple class like this:
class A
{
public:
void f(const int& n)
{
std::cout<<"A::f()" << n <<"\n";
}
};
,我想这样使用:
std::vector<A> vec;
A a;
vec.push_back(a);
std::for_each(vec.begin(), vec.end(), std::bind2nd(std::mem_fun_ref(&A::f), 9));
但是当我编译代码时,我在函数头文件里面得到以下错误:
But when I compile the code I get the following error somewhere inside functional header file:
错误C2529:'_Right':引用
引用是非法的
error C2529: '_Right' : reference to reference is illegal
如果我删除参数f()中的引用,它编译正常。如何解决这个问题?我不想删除引用,因为在我的实际代码复制的对象是相当昂贵的。此外,我不使用boost。
If I remove the reference in the parameter f() it compiles fine. How do I resolve this? I don't want to remove the reference as in my real code the copying of the object is quite costly. Also, I am not using boost.
推荐答案
你不能轻易做到,对不起。只要考虑其中一个没有被 std :: bind1st
和 std :: bind2nd
参数函数等)。 Boost会帮助 - boost :: bind
透明地支持引用,还有 boost :: ref
。
You can't do that easily, sorry. Just consider it one of those cases not covered by std::bind1st
and std::bind2nd
(kinda like 3-argument functions etc). Boost would help - boost::bind
supports references transparently, and there's also boost::ref
.
如果你的实现支持TR1 - 最新的g ++版本和VC ++ 2008 SP1,那么你可以使用 std :: tr1 :: bind
,其大部分与 boost :: bind
相同,但标准化。
If your implementation supports TR1 - latest g++ versions and VC++2008 SP1 both do - then you can use std::tr1::bind
, which is for the most part same as boost::bind
, but standardized.
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