看io_service類裡的成員impl_, 貼幾段程式碼你應該就明白了,

C/C++ code?

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// io_service.hpp

typedef class task_io_service io_service_impl;

...

class io_service: private noncopyable

{

private:

typedef detail::io_service_impl impl_type;

...

impl_type& impl_;

};

C/C++ code?

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// detail/task_io_service.hpp

#include

...

class task_io_service

: public boost::asio::detail::service_base

{

...

reactor* task_;

...

};