On Sat, Apr 17, 2010 at 11:50 AM, Roland Bock <rbock@eudoxos.de> wrote:
Daniel Walker wrote:
On Sat, Apr 17, 2010 at 8:58 AM, Roland Bock <rbock@eudoxos.de> wrote:
Daniel Walker wrote:
On Sat, Apr 17, 2010 at 7:25 AM, Roland Bock <rbock@eudoxos.de> 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 :-)
Exactly. :) And moreover, with respect to TR1/c++0x, is_bind_expression has not been specialized for the function object's type, so it's not treated as a sub-bind expression.
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?
Oh, I was just mentioning it as an aside, because the idiom looks similar; e.g. wrapping things with function<signature>(object). functional_cast can be used to change the signature in order to achieve a polymorphic effect when the underling object can support multiple call signatures. But that's not the issue here. Daniel Walker