Poco中的RunnableAdaptor实现浅析_poco::runnableadapter-优快云博客

本文深入探讨了Poco库中的RunnableAdaptor，它如何作为回调机制实现，类似于boost::function，用于将各种类型的方法和函数对象转换为可线程执行的Runnable接口。

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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。