Poco中的RunnableAdaptor实现浅析

Poco是一个设计相当好的C++框架库。
RunnableAdaptor，继承自Runnable，提供了注册和执行类成员函数的接口。


Runnable的类定义如下：

class Foundation_API Runnable/// The Runnable interface with the run() method/// must be implemented by classes that provide/// an entry point for a thread.{public:Runnable();virtual ~Runnable();virtual void run() = 0;/// Do whatever the thread needs to do. Must/// be overridden by subclasses.};[/c]/// The Runnable interface with the run() method/// must be implemented by classes that provide/// an entry point for a thread.{public:Runnable();virtual ~Runnable();virtual void run() = 0;/// Do whatever the thread needs to do. Must/// be overridden by subclasses.};

这个类设计思想来源JAVA，任何可运行的东西都可以继承自Runnable，只要重写它的run方法。


RunnableAdaptor就是这样一个Runnable，但是它包装了某个类成员函数的注册和执行。也就是说，借用这个RunnableAdaptor就可以执行某个类的成员函数的代码。很有意思。

template <class C>class RunnableAdapter: public Runnable/// This adapter simplifies using ordinary methods as/// targets for threads./// Usage:///    RunnableAdapter<MyClass> ra(myObject, &MyObject::doSomething));///    Thread thr;///    thr.Start(ra);////// For using a freestanding or static member function as a thread/// target, please see the ThreadTarget class.{public:typedef void (C::*Callback)();RunnableAdapter(C& object, Callback method): _pObject(&object), _method(method){}RunnableAdapter(const RunnableAdapter& ra): _pObject(ra._pObject), _method(ra._method){}~RunnableAdapter(){}RunnableAdapter& operator = (const RunnableAdapter& ra){_pObject = ra._pObject;_method  = ra._method;return *this;}void run(){(_pObject->*_method)();}private:RunnableAdapter();C*       _pObject;Callback _method;};

方法就是提供callback，类似于boost::function。