c++ - 来自其他类的 asio 计时器

Question

我试试这个:timer tuto . 但是 void 打印在另一个类中。当我调用 main 中的函数时:

t.async_wait(&class::print);

我有这个错误:

error : must use '.*' or '->*' to call pointer-to-member function in 'boost::asio::detail::lvref<void (class::*)(const boost::system::error_code&)>() (...)', e.g. '(... ->* boost::asio::detail::lvref<void (class::*)(const boost::system::error_code&)>())

我不知道如何解决这个问题:s

You will have to bind the object instance, like: t.async_wait(boost::bind(&Class::print, this, _1)); Or if the instance is not this, use another (smart) pointer that points to a Class. You can use a reference, but that requires a reference wrapper to prevent bind from copying the bound argument: Class c; // ... t.async_wait(boost::bind(&Class::print, boost::ref(c), _1));

我已经试过了，但是我有一个错误:

error : 'void (class::*)(const boost::system::error_code&)' is not a class, struct, or union type typedef typename F::result_type type;

You need to handle the parameter that the print method expects. Something like this: t->async_wait(boost::bind(&Class::print, this, boost::asio::placeholders::error)); Take a look at this tutorial http://www.boost.org/doc/libs/1_59_0/doc/html/boost_asio/tutorial/tuttimer3.html

我试过了，但我有一个我不明白的错误

error : pointer to member type 'void (class::)(const boost::system::error_code&)' incompatible with object type 'windows'
     BOOST_MEM_FN_RETURN (get_pointer(u)->*f_)(b1);
                                        ^

Answer 1

您必须绑定(bind)对象实例，例如:

t.async_wait(boost::bind(&Class::print, this, _1));

或者如果实例不是this，则使用另一个指向Class 的(智能)指针。您可以使用引用，但这需要引用包装器来防止绑定(bind)复制绑定(bind)参数:

Class c;

// ...
t.async_wait(boost::bind(&Class::print, boost::ref(c), _1));