Re: wrapping synchronization in objects?

SG <>
Wed, 1 Apr 2009 10:12:00 -0700 (PDT)
On 1 Apr., 17:47, "Gernot Frisch" <> wrote:

is it possible (win32, *nix, only) to create a template class that
locks/unlocks a mutex every time the value of an object is used?

I recently saw a nifty trick that involves a smart pointer that locks
a mutex upon "use" of its pointee.

The trick was to let operator-> return a proxy (local rvalue) that
locks the mutex in the constructor, unlocks it in the destructor and
also overrides operator-> to return the actual pointer.

   void f(lockptr<my_class> p const&)

would be short for

   void f(lockptr<my_class> p const&)

After the first ->() you have a temporary. This temporary's ->()
returns the actual pointer which is then used to call the function.
The temporary is destroyed when the complete expression is evaluated
(including the function call do_something). Locking and unlocking is
done in the temporary's constructor and destructor.


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