mem_fun和bind1st问题 [英] mem_fun and bind1st problem

问题描述

我有以下类：

class A {
public:
// ctr and etc ...
A*   clone(B* container);
};

现在，我有一个向量< A *> availableObjs 已填充。我想在其中的每一个上调用 clone ，因此将克隆的对象插入一个新的容器 clonedObjs 类型 vector< A *> 。我试图跟着 - 但它不编译：

Now, I've a vector<A*> availableObjs populated already. I want to call clone on each of those, so and insert cloned objects into a new container clonedObjs of type vector<A*>. I'm trying following - but it doesn't compile:

transform(availableObjs.begin(), availableObjs.end(), back_inserter(clonedObjs),
    bind1st(mem_fun(&A::clone), container)); // container is of type B*

有一个简单的方法吗？

Is there a easy way out? I've a lot classed like A - so making each of those a functor is too much task.

推荐答案

您需要使用 bind2nd 而不是 bind1st ：

transform(availableObjs.begin(), availableObjs.end(), back_inserter(clonedObjs),
    bind2nd(mem_fun(&A::clone), container)); // container is of type B*

mem_fun ; A :: clone）期望一个 A * 作为它的第一个参数。这是在其上调用该方法的通常隐式指定的实例。 A :: clone 的第一个真实参数是 mem_fun（& A :: clone），因此需要绑定 bind2nd 。

The functor created by mem_fun(&A::clone) expects an A* as its first parameter. This is the normally implicitly specified instance on which the method is called. The first "real" parameter of A::clone is the second parameter of mem_fun(&A::clone) and therefore needs to be bound with bind2nd.

这篇关于mem_fun和bind1st问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！