Re: bind guard ?

From:

"Maxim Yegorushkin" <maxim.yegorushkin@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

7 Aug 2006 08:52:21 -0400

Message-ID:

<1154944959.023034.168750@m73g2000cwd.googlegroups.com>

Buster wrote:

I'd like to have an arbitrary function with arguments
called when execution leaves a function, either
normally or because of an exception. I assumed
there was a boost structure, not unlike a semaphore
guard, that took a generic function object but
I can't find one. Does such a thing exist ?

void func1(int);
void func2();

void func3()
{
    guard G(make_guard(bind(&func1, 5)));

    func2();

    G.release();
}

You can make one yourself easily:

namespace detail {

class scope_guard_base
{
public:
     void release() const { do_rollback_ = false; }

     scope_guard_base() : do_rollback_(true) {}

     scope_guard_base(const scope_guard_base& other)
         : do_rollback_(other.do_rollback_)
     {
         other.release();
     }

protected:
     mutable bool do_rollback_;
};

template<class F>
class scope_guard_impl : public scope_guard_base
{
public:
     explicit scope_guard_impl(F const& b)
         : rollback_(b)
     {}

     ~scope_guard_impl()
     {
         if(do_rollback_)
             rollback_();
     }

private:
     F rollback_;
};

} // namespace detail

typedef const detail::scope_guard_base& scope_guard;

template<class F>
inline detail::scope_guard_impl<F> make_guard(F const& f)
{
     return detail::scope_guard_impl<F>(f);
}

Another one can be found here:
http://boost.cvs.sourceforge.net/boost/boost/boost/multi_index/detail/scope_guard.hpp?revision=HEAD&view=markup

      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]