Re: [Boost-users] threads - basic introduction

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-02-15 19:03:51

Noah Roberts wrote:

> void start_new_connection()
> {
>   ...
>   boost::thread connection_thread(connection_thread_proc(l,s));
> }
>
> Originally I assumed that there would be problems with this since my
> thread object goes out of scope so I figure the connection_thread_proc
> it holds should be destroyed along with it...and with it important
> objects like the listener and the tcp connection.  So I was working on
> this convoluted way to store threads and check their state...which
> boost doesn't support out of the box it looks like and I was going to
> have to add yet another wrapper to the pile...so I decided to try and
> see if it did indeed explode and it doesn't.
>
> The question is, am I looking at undefined behavior that happens to
> work correctly or is this by design?

It works by design. The constructor of boost::thread makes a private copy of 
the function object and keeps it alive until its operator() returns. The 
boost::thread object itself is irrelevant, the function object is part of 
the thread state block kept by the newly spawned thread.

You can use boost::bind( &Listener::run, l, s ) instead of writing a 
function object by hand, although I don't know how it will react to your ^ 
thingies. :-)