Re: [Boost-users] [boost] Boost.Local Review (Nov 10, 2011 to Nov 19, 2011)

Subject: Re: [Boost-users] [boost] Boost.Local Review (Nov 10, 2011 to Nov 19, 2011)
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-11-16 13:21:21

Le 16/11/11 16:41, Paul A. Bristow a écrit :
>
> *From:*boost-users-bounces_at_[hidden] 
> <mailto:boost-users-bounces_at_[hidden]>[mailto:boost-users-bounces_at_[hidden]] 
> <mailto:[mailto:boost-users-bounces_at_[hidden]]>*On Behalf Of 
> *Jeffrey Lee Hellrung, Jr.
> *Sent:* Thursday, November 10, 2011 5:53 AM
> *To:* boost-announce_at_[hidden] 
> <mailto:boost-announce_at_[hidden]>; boost-users_at_[hidden] 
> <mailto:boost-users_at_[hidden]>
> *Subject:* [Boost-users] [boost] Boost.Local Review (Nov 10, 2011 to 
> Nov 19, 2011)
>
> The review of Lorenzo Caminiti's proposed Boost.Local library begins 
> tomorrow, ***November 10, 2011***, and ends on ***November 19, 2011***.
>
> Other questions you may want to consider:
>
> - What is your evaluation of the design?
>
> I have some concern about manipulation of C++ to do things it wasn't 
> really designed to:
>
> if C++ is intended to have local functions, it should be part of the 
> language.
>
If I'm not wrong lambdas play a role similar to unnamed local functions, 
and they are already in the language. The intent of Boost.Local is to 
provide something similar on compilers that doesn't support lambdas.
>
> 'Abuse' like this tends to cause trouble, and more important, it puts 
> off the day when we abandon this "absurdly ambiguous language" in 
> favour of new language X (or have we run out of letters for new 
> languages? ;-) un-shackled by any primitive and obsolete features 
> inherited from C.
>
Well, you know, the first uses of exceptions and templates in C++ were 
possible thanks to some preprocessor magic libraries. While incomplete, 
these 'emulations' allowed to some of us to start using these features 
and surely pushed to include them properly on the language later on. The 
preprocessor is a really useful tool that has his place in such contexts.

Unfortunately, the local function emulation needs to bind explicitly the 
used variables. I think, that even with lambdas in the language, local 
functions will have his place, as soon as they provide access to the 
enclosing function data.
>
> But that hasn't stopped many people making good use of such devices, 
> for example, Boost.Parameter.
>
Yes this is another example of things that could be included in the 
language and in this case that can be emulated using a library.

I understand that a language can not include all the features desired by 
each user, and that there could be other missing features with a higher 
added value, but there is one feature that I think is missing in C++: 
the scoped exit/success/failure as defined in language D. I hope the 
emulation of Boost.ScopedExit or Boost.Local could show its usefulness 
and that someone will make a concrete proposal to the standard committee.

Best,
Vicente