推迟函数执行方法

#include <iostream>
#include <string>
#include <memory>

#define defer(fun,p) std::shared_ptr<void> defer_##p(p,std::bind(fun,std::placeholders::_1))
void fun(int *p) {
    std::cout << "p = " << *p << std::endl;
}
int main() {
    int a = 10;
    int *p = &a;
    defer(fun, p);
    std::cout << "hello world." << std::endl;
    
    return 0;
}