std::remove_if 使用其他类方法

2021-12-23 00:00:00 methods c++ predicate stdvector remove-if

我想将 std::remove_if 与作为差异类成员函数的谓词一起使用.

I want to use std::remove_if with a predicate that is a member function of a differenct calss.

那就是

class B;

class A {
    bool invalidB( const B& b ) const; // use members of class A to verify that B is invalid
    void someMethod() ;
};

现在，实现A::someMethod，我有

void A::someMethod() {
    std::vector< B > vectorB; 
    // filling it with elements

    // I want to remove_if from vectorB based on predicate A::invalidB
    std::remove_if( vectorB.begin(), vectorB.end(), invalidB )
}

有没有办法做到这一点?

Is there a way to do this?

我已经研究了解决方案用于 remove_if 的惯用 C++，但它处理的情况略有不同，即remove_if 是 B 而不是 A 的成员.

I have already looked into the solution of Idiomatic C++ for remove_if, but it deals with a slightly different case where the unary predicate of remove_if is a member of Band not A.

此外，
我无权使用 BOOST 或 c++11

Moreover,
I do not have access to BOOST or c++11

谢谢！

推荐答案

一旦你在 remove_if 中，你就失去了 this 指针A.所以你必须声明一个功能对象，它包含它，例如:

Once you're in remove_if, you've lost the this pointer of A. So you'll have to declare a functional object which holds it, something like:

class IsInvalidB
{
    A const* myOwner;
public:
    IsInvalidB( A const& owner ) : myOwner( owner ) {}
    bool operator()( B const& obj )
    {
        return myOwner->invalidB( obj );
    }
}

只需将它的一个实例传递给 remove_if.

Just pass an instance of this to remove_if.

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