您可能希望将this指针捕获到c++ lambda中,但这将捕获原始指针。如果需要延长对象的生命周期,则需要捕获强引用。“捕获对自己的强引用”的常见模式是同时捕获强引用和原始this。强引用保持this为活的,并且使用this方便访问成员。
#include <functional>
#include <IOStream>
#include <memory>
#include <string>
std::vector<std::function<void(void)>> actions;
class Widget : public std::enable_shared_from_this<Widget> {
public:
Widget(const std::string name){name_ = name;}
void reg() {
// std::shared_ptr
auto callback = [lifetime = shared_from_this(), this]() {
action(name_);
};
actions.push_back(callback);
}
virtual void action(std::string name) {
std::cout << "widget action:" << name << std::endl;
}
std::string name_;
};
class Table : public Widget {
public:
Table(const std::string name):Widget(name){}
virtual void action(std::string name) {
std::cout << "table action:" << name << std::endl;
}
};
void reg_action() {
auto widget = std::make_shared<Widget>("widget");
widget->reg();
auto table = std::make_shared<Table>("table");
table->reg();
}
int mAIn(int argc, char* argv[]) {
reg_action();
for (const auto& action : actions) {
action();
}
}
输出:
widget action:widget
table action:table
在线测试
https://wandbox.org/permlink/HDrKO6Hn6tROiVEj
#include <functional>
#include <iostream>
#include <memory>
std::vector<std::function<void(void)>> actions;
class Widget : public std::enable_shared_from_this<Widget> {
public:
void reg() {
actions.push_back(std::bind(&Widget::action, shared_from_this()));
}
virtual void action() {
std::cout << "widget action" << std::endl;
}
};
class Table : public Widget {
public:
virtual void action() {
std::cout << "table action" << std::endl;
}
};
void reg_action() {
auto widget = std::make_shared<Widget>();
widget->reg();
auto table = std::make_shared<Table>();
table->reg();
}
int main(int argc, char* argv[]) {
reg_action();
for (const auto& action : actions) {
action();
}
}
输出:
widget action
table action