这两天被vs2010的std::tr1::bind郁闷了

    std::tr1::function<bool(bool)> f4 = 
        std::tr1::bind(
            std::logical_and<bool>(),
            std::tr1::bind(std::logical_not<bool>(), std::tr1::placeholders::_1),
            true);

想在vs2010里玩一玩function programming,却被郁闷了,又发现了一个别人发现过的bug

A bug about std::tr1::bind 

 

请输入评论。

由 Microsoft 在 2009/8/7 18:33 发送

Hi,

Thanks for reporting this bug. Unfortunately, we have resolved it as Won't Fix for VC10. Our implementation is fragile when it comes to nested bind(), and we'll need to devote significant time to fixing it - time we don't have for VC10. (I can't promise anything, but I hope to be able to rewrite bind()'s implementation when we get variadic templates.)

The good news is that lambdas in VC10 supersede bind() in 99% of cases. Lambdas offer much more natural syntax (especially compared to nested bind()) and greater efficiency, since the optimizer can inline lambdas but has difficulty with bind()'s functors.

Here's an example that expresses your bind() functor as a lambda (doing something slightly different with it, but the functor has the same behavior):

C:\Temp>type meow.cpp
#include <algorithm>
#include <iostream>
#include <iterator>
#include <ostream>
#include <vector>
using namespace std;

int main() {
    vector<int> v;
    v.push_back(2);
    v.push_back(4);
    v.push_back(6);
    v.push_back(8);
    v.push_back(1);
    v.push_back(3);
    v.push_back(5);
    v.push_back(7);
    v.push_back(9);

    vector<int> dest;

    copy_if(v.begin(), v.end(), back_inserter(dest), [](int n) { return n >= 3 && n <= 8; });

    for_each(dest.begin(), dest.end(), [](int n) { cout << n << " "; });
    cout << endl;
}

C:\Temp>cl /EHsc /nologo /W4 meow.cpp
meow.cpp

C:\Temp>meow
4 6 8 3 5 7

Until you get VC10, remember that handwritten functors are always an alternative to using bind().

If you have any further questions, feel free to E-mail me at stl@microsoft.com .

Stephan T. Lavavej
Visual C++ Libraries Developer

由 Microsoft 在 2009/4/22 23:36 发送

Thanks for your feedback.

We are escalating this issue to the appropriate group within the Visual Studio Product Team for triage and resolution. These specialized experts will follow-up with your issue.

Thank you,
Visual Studio Product Team

 

 

只好换boost或者lambda