Re: a really simple C++ abstraction around pthread_t...

From:
"Chris M. Thomasson" <no@spam.invalid>
Newsgroups:
comp.lang.c++,comp.programming.threads
Date:
Sun, 9 Nov 2008 04:12:17 -0800
Message-ID:
<uqARk.2275$lo6.817@newsfe01.iad>
"Ulrich Eckhardt" <doomster@knuut.de> wrote in message
news:6nh95gFlmtc6U1@mid.uni-berlin.de...

Responding late, it was a rough week...

[...]

In any case, you can write an equivalent program using Boost.Thread. If
you
want, you can wrap stuff into a class, e.g. like this:

struct active_person
{
  explicit active_person(queue& out_):
    out(out_),
    th( bind( &handle_requests, this))
  {}
  ~active_person()
  { th.join(); }
  void push_question( std::string const& str)
  { in.push(str); }
  std::string pop_answer()
  { return out.pop(); }
private:
  void handle_requests()
  {
    while(true)
    {
      std::string question = in.pop();
      if(question=="QUIT")
        return;
      out.push(p.ask(question));
    }

      out.push("QUIT");

  }
  queue in;
  queue& out;
  person p;
  // note: this one must come last, because its initialisation
  // starts a thread using this object.
  boost::thread th;
};


[...]

I would create the active template using Boost like:

// quick sketch - may have typo
_______________________________________________________________________
template<typename T>
class active : public T {
  boost::thread m_active_handle;

public:
  active() : T(), m_active_handle(bind(&on_active, (T*)this)) {}

  ~active() { m_active_handle.join(); }

  template<typename P1>
  active(P1 p1) : T(p1),
    m_active_handle(bind(&on_active, (T*)this)) {}

  template<typename P1, typename P2>
  active() : T(P1, P2),
    m_active_handle(bind(&on_active, (T*)this)) {}

  // [on and on for more params...]
};
_______________________________________________________________________

Then I could use it like:

struct person {
  void on_active() {
    // [...]
  }
};

int main() {
  active<person> p[10];
  return 0;
}

I personally like this construction; I think its "cleaner" than using the
Boost interface "directly".

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