Re: [boost] optional<optional<T>>

Subject: Re: [boost] optional<optional<T>>
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-09-03 06:59:28

On Thu, Sep 3, 2009 at 3:45 AM, Richard
Webb<richard.webb_at_[hidden]> wrote:
>
>
> OvermindDL1 wrote:
>>
>>
>> Slightly off-topic, but I consider D to be a *fascinating* language,
>> kind of like how C++ should have been. Â It would actually be *much*
>> easier to create Spirit in D then it would have been in C++, and you
>> could have used real PEG syntax instead of C++/D'ifying it.
>>
>>
>
> I've been looking at D a bit myself recently, and i just saw this on the D
> mailing list:
> http://lists.puremagic.com/pipermail/digitalmars-d-announce/2009-August/013978.html

<still off-topic>

Heh, interesting, but they are going about it the completely wrong
way.  First Spirit 1's design is quite a bit more convoluted then
Spirit2's.
Second, thanks to mixin's and the fact that templates can operate on
strings in D (not just integers and types like in C++), they could
implement a *real* PEG syntax that gets completely lowered to pure D
code at compile-time.

Yes, D is that powerful.  Heck, if C++ added D style templates and
mixin support and compile-time functions (which I guess is kind of
getting added to C++1x), I would be happier then you could believe.
:)

For an example, I even saw a pure compile-time regex parser that you use like:
static_regex!("gh.+a") r;
regex_info info = r(someString);

In D a template is !() unlike in C++ where it is <>.  I personally
like <> better since I am used to it, but !() is certainly easier to
parse and is unambiguous...
But yes, that regex is completely lowered to pure D code at compile
time, ala Boost.Xpressive's static regex parser.

D really does mix in a lot of LISP's power into a C++ syntax (not all
of LISP's power, but it gets *REALLY* close).