Re: [boost] [multiindex] internal scope_guard has changed access from public to protected

Subject: Re: [boost] [multiindex] internal scope_guard has changed access from public to protected
From: Jeffrey Lee Hellrung, Jr. (jhellrung_at_[hidden])
Date: 2010-05-30 16:49:39

On 5/30/2010 2:39 AM, Joaquin M Lopez Munoz wrote:
> Thorsten Ottosen<thorsten.ottosen<at>  dezide.com>  writes:
[...]
>> Joaquin, what is your take on this?
>
> I concur with Jeff's poins of view in both respects:
>
> * make_guard_if<cond>  should construct the guard if cond is true
> (I overlooked the fact that your implementation does the opposite, sorry).
> I think this is the obvious semantics for anyone reading the construct:
> make a guard if so and so.
> * It'd be nice if we have both the following:
>
>    template<typename IsNull, ...>
>    inline typename null_guard_return<..>::type
>    make_guard_if(...)
>
>    template<bool is_null, ...>
>    inline typename null_guard_return<..>::type
>    make_guard_if_c(...)

Of course, you mean IsNonNull / is_non_null (or equivalent semantics) 
for the template parameters...

> just like enable_if and enable_if_c, which is probably the closest
> existing practive we've got in Boost.
>
> As for make_guard_unless (and make_guard_unless_c) I guess it's
> up to you to provide it also, at the risk of being a little
> overabundant at providing variations on the same basic theme.

There *is* disable_if / disable_if_c, and even lazy_* versions, so there 
is precedent at very explicitly providing such variations.

- Jeff