Re: [boost] ScopeExit

From: Steven Watanabe (steven_at_[hidden])
Date: 2007-08-20 16:02:57

AMDG

Christian Holmquist <c.holmquist <at> gmail.com> writes:

> Let's say I have two Worlds, and would like to add one person into each of
> these.I would prefer to write that like:
> 
> boost::scope_guard guard;
> World world1, world2;
> 
> world1.addPerson(guard, Person(...));
> world2.addPersion(guard, Person(...));
> 
> guard.commit();
> 
> With the current proposal I don't see how I this could be done, since there
> is no visible notion of a context keeping the guards.
> 
> For my own work i've written a simple scope_guard that holds a
> std::vector<boost::function>, where I add all lambda expressions to be
> invoked unless I call scope_guard::commit(). This works but the lambda mess
> remains.

That isn't exception safe because
1) push_back can throw
2) function::function can throw

You can think of the bool commit as the context keeping
the guards.  Unless you set it all the ScopeExit rollback
actions will be executed exactly as in your example.

In Christ,
Steven Watanabe