Re: [boost] Re: Threads docs updated in CVS

From: Douglas Gregor (gregod_at_[hidden])
Date: 2001-08-15 20:32:05

On Wednesday 15 August 2001 09:17, you wrote:
> > Well, the preferred method shortens the pattern a little:
> >
> > {
> >    mutex::scoped_lock lock(m);
> >    cv.wait(lock, pred);
> >    action();
> > }
> >
> > It's not really possibly to shorten things beyond this.
>
> 	Well, you can write:
>
> 	template<class Action, class Pred> struct caction
> 	{
> 		void run() {
> 			mutax.scope_lock lock(m);
> 			cv.wait(lock, pred);
> 			action();
> 		}
> 		caction(mutex &m_a, Pred const &pred_a, Action &action_a)
>
> 		: m(m_a), pred(pred_a), action(action_a) { run(); }
>
> 		mutex &m;
> 		Pred const &pred;
> 		Action &action;
> 	};
>
> 	mutex m; ..
> 	Pred pred(..);
> 	Action action(..);
> 	cation<Action, Pred>(m, pred, action);
>
> Of course, the templatisation is basically useless due to the lack
> of nested function closures, which force you to declare the types
> Pred and Action out of line (instead of defining inline anonymous
> functions like you would in a functional programming language).
> But then, by this argument, STL is basically rendered useless
> by lack of core language support, so YMMV.

Boost.Function can eliminate the need for the template parameters:
typedef boost::function<void> Action;
typedef boost::function<bool> Pred;

A library like Lambda, Boost.Bind, or FACT would let you define the predicate 
and action inline.

        Doug