(2)template <classRet,classFn,class... Args>/*unspecified*/bind (Fn&& fn, Args&&... args); bind返回一个基于fn的函数对象(function object), 其参数被绑定到args上. fn的参数要么是绑定到值,要么是绑定到placeholders(占位符,如_1, _2, …, _N) 参数: fn: 一个可调用对象(可以是function obj...
根据cppreference对第二种情况的描述: • If the stored argumentargis of typeTfor which std::is_bind_expression ::value == true (for example, anotherbindexpression was passed directly into the initial call tobind), thenbindperforms function composition: instead of passing the function object that...
Callable object (function object, pointer to function, reference to function, pointer to member function, or pointer to data member) that will be bound to some arguments args - 要绑定的参数列表,未绑定参数为命名空间 std::placeholders 的占位符 _1, _2, _3... 所替换 注解 如可调用 (Callable...
#include <functional> #include <iostream> void f(int& n1, int& n2, const int& n3) { std::cout << "In function: " << n1 << ' ' << n2 << ' ' << n3 << '\n'; ++n1; // increments the copy of n1 stored in the function object ++n2; // increments the main()'s n2 ...
std::function<void(const std::string &)> update_; private: void Update(const std::string...
; // returns ten_two.a std::cout << bound_member_data() << '\n'; // 10 return 0; } By default, bind makes a copy of the provided function object. boost::ref and boost::cref can be used to make it store a reference to the function object, rather than a copy. This can ...
std::function<void(conststd::vector<Touch*>&, Event*)> onTouchesBegan; AI代码助手复制代码 因为CC_CALLBACK系列是std::bind,而onTouchesBegan是std::function来定义的。那么std::bind和std::function又有什么区别呢? 有博文说: function模板类和bind模板函数,使用它们可以实现类似函数指针的功能,但却比函数指...
Case 1: reference wrappers Ifarg_iis of typestd::reference_wrapper<T>(for example,std::reforstd::crefwas used in the initial call tostd::bind), thenv_iisarg_i.get()and its typeV_iisT&: the stored argument is passed by reference into the invoked function object. ...
cref 则是const reference void f(int& n1, int& n2, const int& n3) { std::cout << "In function: " << n1 << ' ' << n2 << ' ' << n3 << '\n'; ++n1; // increments the copy of n1 stored in the function object
错误消息 "cannot bind non-const lvalue reference of type ‘std::string&’" 表明你尝试将一个非常量左值引用绑定到一个右值(rvalue)上。右值通常指的是临时对象或字面量,它们是不可修改的。由于非常量左值引用期望能够修改它所引用的对象,因此这种绑定会违反C++的类型安全规则,从而导致编译器报错。 3. 出现...