能够使用指针来调用外部类的私有方法 [英] Able to use pointer to function to call private method of an external class
问题描述
基于以下回答到最近的 question ,我可以使用函数指针来调用来自另一个类的私有方法 Foo< T> :: foo()
Bar
,如下所示(另请参阅 ideone )
Based on the following answer to a recent question, I'm able to use a function pointer in order to call the private method Foo<T>::foo()
from another class Bar
, as shown below (see also ideone)
#include <iostream>
template<typename T>
struct Bar
{
typedef void (T::*F)();
Bar( T& t_ , F f ) : t( t_ ) , func( f )
{
}
void operator()()
{
(t.*func)();
}
F func;
T& t;
};
template<typename T>
class Foo
{
private:
void foo()
{
std::cout << "Foo<T>::foo()" << std::endl;
}
public:
Foo() : bar( *this , &Foo::foo )
{
bar();
}
Bar<Foo<T> > bar;
};
int main()
{
Foo<int> foo;
}
这适用于MSVC 2013和GCC 4.8.3。
This works on MSVC 2013 and GCC 4.8.3. Is it valid?
推荐答案
是的,它是可以的,它可以工作。
Yes it is permissible, and it works.
C ++ Programming by Bjarne Stroustoup
C ++防止意外而非故意规避
(欺诈)
C++ protects against accident rather than deliberate circumvention (fraud)
<当然,你不能直接/轻松地调用类外的私有方法,但如果你做足够的努力,C ++将允许它。
Sure, you cannot directly/easily call private methods outside the class, but if you are making enough efforts, C++ will allow it.
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