Subject: Re: [boost] [Bind] How do I get bind to deduce the return type of for_each?
From: Roland Bock (rbock_at_[hidden])
Date: 2010-04-17 11:50:15
Daniel Walker wrote:
> On Sat, Apr 17, 2010 at 8:58 AM, Roland Bock <rbock_at_[hidden]> wrote:
>
>> Daniel Walker wrote:
>>
>>> On Sat, Apr 17, 2010 at 7:25 AM, Roland Bock <rbock_at_[hidden]> wrote:
>>>
>>>> for_each(vov.begin(), vov.end(),
>>>> bind(for_each< vocType::iterator, function<void (myClass&)> >,
>>>> bind<vocType::iterator>(&vocType::begin, _1),
>>>> bind<vocType::iterator>(&vocType::end, _1),
>>>> protect(bind(&myClass::func, _1))
>>>> )
>>>> );
>>>>
>>>>
>>> Oh yeah, that's a good idea! Instantiate std::for_each with a void
>>> boost::function! That's a portable solution as well, since bind and
>>> function are available on practically any compiler, even ancient,
>>> substandard ones.
>>>
>>> Daniel Walker
>>>
>>>
>>>
>> Thanks :-)
>>
>> Btw, could I do the same with tr1::bind? What would be the equivalent of
>> boost::protect?
>>
>
> Yeah, you can do the same thing in TR1. Instead of boost::protect, you
> can just use tr1::function, again. :)
>
> for_each(vov.begin(), vov.end(),
> bind(for_each< vocType::iterator, function<void (myClass&)> >,
> bind<vocType::iterator>(&vocType::begin, _1),
> bind<vocType::iterator>(&vocType::end, _1),
> function<void(myClass&)>(bind(&myClass::func, _1))
> )
> );
>
> Actually, I once wrote a functional_cast (analogous to lexical_cast)
> that did something like that. It's in vault.
>
> Daniel Walker
>
OK, got it, the function object kind of digests the inner _1 before the
outer bind can lay its fingers on it :-)
Just took a look at the polymorphic_function and functional_cast. I'll
have to try and remember it, because I am sure I had use cases for that
in the past (obviously solved them in another way). How would you apply
them to the current topic?
Regards,
Roland