[英]How to call any class function using its pointer if we know arguments and return type?
How to create a function pointer to any class function knowing only arguments and return type?如何创建一个指向任何只知道参数和返回类型的类函数的函数指针? How to call this function later?以后怎么调用这个函数?
I read about std::function, however I do not have an idea how to implement it without using specific class name like " std::function<void(const ClassName&, int)> f_add_display = &ClassName::func;
"我读过 std::function,但是我不知道如何在不使用特定类名的情况下实现它,例如“ std::function<void(const ClassName&, int)> f_add_display = &ClassName::func;
”
The example below is NOT for compiling, it is only to show the idea I mean:下面的例子不是为了编译,它只是为了展示我的意思:
class collection {
p* ...; //pointer to any(!) class function with known arguments and return type
} _collection;
class One {
public:
...
bool Foo_1(int, int) {};
void saveFuncAddr() {_collection.p = this::Foo_1};
};
class Two {
public:
bool Foo_2(int, int) {};
void saveFuncAddr() {_collection.p = this::Foo_2};
};
int main() {
one* = new One();
one->saveFuncAddr();
bool res1 = (*_collection.p)(1, 2);
two* = new Two();
two->saveFuncAddr();
bool res2 = (*_collection.p)(1, 2);
}
First, identifiers beginning with an underscore is reserved in the global namespace , so you shouldn't declare a name like _collection
.首先,以下划线开头的标识符在全局命名空间中保留,因此您不应声明像_collection
这样的名称。
You can use lambdas to wrap your member functions:您可以使用 lambdas 来包装您的成员函数:
#include <functional>
struct Collection {
std::function<bool(int, int)> p;
} collection;
class One {
public:
bool Foo_1(int, int) {return true;}
void saveFuncAddr()
{
collection.p = [this](int a, int b){return this->Foo_1(a, b);};
}
};
class Two {
public:
bool Foo_2(int, int) {return true;}
void saveFuncAddr()
{
collection.p = [this](int a, int b){return this->Foo_2(a, b);};
}
};
int main() {
auto one = new One();
one->saveFuncAddr();
bool res1 = (collection.p)(1, 2);
delete one;
auto two = new Two();
two->saveFuncAddr();
bool res2 = (collection.p)(1, 2);
delete two;
}
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