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

Subject: Re: [boost] Boost.Local Review (Nov 10, 2011 to Nov 19, 2011)
From: Lorenzo Caminiti (lorcaminiti_at_[hidden])
Date: 2011-11-14 19:59:43

On Mon, Nov 14, 2011 at 7:25 PM, Jeffrey Lee Hellrung, Jr.
<jeffrey.hellrung_at_[hidden]> wrote:
> On Mon, Nov 14, 2011 at 4:00 PM, Lorenzo Caminiti <lorcaminiti_at_[hidden]>wrote:
> [...]
>
>> As it was suggested, I'm thinking that I will change from this_ to
>> _this (to be consistent with Phoenix) and require to use _this in both
>> the local function declaration and implementation (and error at
>> compile-time if you use this instead of _this in the declaration but I
>> still can't error if you mistakenly use this instead of _this in the
>> definition :( ). I will also leave the config macro so the users can
>> change this name if they want/need to.
>>
> [...]
>
> I think it would be more consistent with other Boost libraries to use
> "this_" rather than "_this".
>
> A leading underscore is used to distinguish domain-defined keywords and
> placeholders.  This *kind of* fits that, but...well, to me, not exactly.
>
> On the other hand, one would almost certainly prefer to just use "this",
> except...you can't.  Anytime you want to use a C++ keyword as an identifier

Yes, I can't :( This is marked in the Tutorial as Warning. The only
way I could figure out it's illegal because it relies on an undefined
behavior of static_cast (see Tutorial section footnote #13):
http://groups.google.com/group/comp.lang.c++.moderated/browse_thread/thread/d3a86f27277f713b

> but can't actually use the keyword verbatim, the consistent practice has
> been to append an underscore.
>
> Just my opinion, and it's not a big deal either way,

In this email thread:
http://lists.boost.org/Archives/boost/2011/04/179834.php

Three things where pointed out:
1) _ prefix is for placeholders.
2) _ postfix is for keywords.
3) Boost.Phoenix already uses _this (as a placeholder).

In the Boost.Local case _this/this_ is both:
1) A placeholders because it will be "replaced" with the actual object
pointer `this`.
2) And obviously a keyword.
So what do I do? _this or this_?

I might as well be consistent with another Boost library. Plus, if
_this is also used in the function declaration (not just the
definition) then it really acts as a placeholder. I am only 52% in
favor of _this over this_ and I am happy to use the name that the
reviewers find more correct.

BTW, I couldn't find Phoenix docs that refer to _this-- does anyone
have a link? Is there any other Boost library that uses either _this
or this_?

Thanks,
--Lorenzo