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Subject: Re: [boost] Review of Local Exits
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-11-19 18:39:01

Le 19/11/11 23:08, Lorenzo Caminiti a écrit :
> On Sat, Nov 19, 2011 at 3:59 PM, Alexander Nasonov<alnsn_at_[hidden]> wrote:
>> This is not a full review of the proposed Boost.Local library, I've
>> reviewed only Local Exits and a potential merge with Boost.ScopeExit.
> Hello Alex and thank you very much for your comments.
>> I vote NOT to merge Local Exits with Boost.ScopeExit for the following
>> reasons:
> I have no problem with local exits and scope exits remaining separate.
> Local exits will additionally provide no bindings (void), const
> bindings, and binding of this_.
>> - Local Exits feature gives two different interfaces ("variadic" and
>> "sequencing"). In my opinion, it should only document C++0X
>> interface and have a section called something like "What if I don't
>> have a C++0X compliant compiler?" where it will explain an
> Yes, the same comment was made by Vicente and Thomas for the entire
> Boost.Local. I am happy to just document the variadic syntax and have
> an Annex with the sequencing syntax.
>> alternative interface for a transitional period.
>> Some compilers already support enough C++0X features to let you
>> develop a "perfect" interface.
>> - Binding of variables should be modeled after lambda captures. This
>> means no this_ and no void. I really like void and I'd added it if
>> Lorenzo came up with the idea at the time when Boost.ScopeExit was
>> still in development.
> FYI, I can write pp code that transforms void, this_, etc into lambda
> captures. For example:
> TO_CAPTURE(void) // expand to []
> TO_CAPTURE(this_,&x) // expand to [this,&x]
> TO_CAPTURE( (this_) (&x) ) // expand to [this,&x]
> This way SCOPE_EXIT(void) and SCOPE_EXIT( (this_) (&x) ) or even
> SCOPE_EXIT(this_,&x) could support void and this_ while still working
> on both C++03 and C++11...
>> - For the same reason, const bind& and bind& should be removed from
>> the interface.
> Well, if local exits are not merged with scope exits, local exits can
> keep const bind&, bind&, this_, void, etc.

Hi Lorenzo,
I wouldn't want two libraries providing Scope Exit idiom in Boost with
only a minor binding difference, this will be confusing. I don't know if
you have explained this in the document , but could you try to explain
here (or point where in the documentation) what are the clear advantages
of capturing void, this or capturing by const&.

Alex, could you explain why (a part form following the lambda capture),
you don't want to accept these new bindings in ScopedExit?


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