Re: [boost] ScopeExit

From: Alexander Nasonov (alnsn_at_[hidden])
Date: 2007-08-20 12:44:35

Giovanni Piero Deretta <gpderetta <at> gmail.com> writes:

> I use boost lambda expression extensively, and I have a love/hate
> relationship with
> them.  When you finally get a (complex) lambda to compile it might
> even be elegant and even readable, but getting there requires an
> inordinate amount of time.

:-)

> I do not have time right now for a review (I will try late this
> evening), but I think that the "inline" lambda capabilities of
> ScopeExit and its ScopeGuard-like functionality should be decoupled.
> The trick used by ScopeExit could be much more useful as a generalized
> (named) closure mechanism. These closures could then be used with the
> classic ScopeGuard idiom, to emulate what ScopeExit does right now,
> but could also replace most usages of boost lambda.
> Anyone would find such a mechanism useful? Alexander, do you think
> that it would be hard to extend ScopeExit to a generalized closure? I
> have done some experiments in the past with something like that and it
> seemed doable.

The problem is that ScopeExit relies on local structs which can't
be used in templates.

If you look at Implementation section ( http://tinyurl.com/2gerqy )
you'll notice params_1_t and scope_exit_body_t local structures.

Though, I see how it can be avoided: (void*) new params_1_t(...).

I should play with this idea. May be I'll be able to come up with
a good syntax for a generalized closure ;-)

--
Alexander