Re: [boost] [bind] recursively binding higher-order functional objects fails to compile.

From: Martin Bonner (Martin.Bonner_at_[hidden])
Date: 2008-02-20 10:23:20

From: Korcan Hussein
Sent: 20 February 2008 15:06 To: boost_at_[hidden]
Subject: [boost] [bind] recursively binding higher-order functional
objects fails to compile. 

> Sorry about the poor title, it is difficult for me to explain the
> problem without code so here is a really simple example of what i'm
> trying to achieve but fails to compile with Boost.Bind:
> 
> #include <boost/bind.hpp>
> 
> struct FunFn {
> 
> 	typedef void result_type;
> 	template < typename Fun >
> 	void operator()(Fun fn) const {
> 		fn();
> 	}
> 
> } const Fn;
> 
> void g() { std::cout << "hello\n"; }
> 
> int main() {
> 	using namespace boost;
> 
> 	bind(Fn, bind(Fn, bind(Fn, bind(Fn, ... bind(Fn, g))();

Clearly:
      bind(Fn,g)();
works.  What about:

      bind(Fn, bind(Fn, g))();

If that works, how many binds can you add before it stops working?
      
> 
> }
> 
> I get type deduction errors, 

You may have run into a compiler limit.  What compiler are you using?

> however i have found workaround using
> Boost.Function for the time being:
> 
> #include <boost/function.hpp>
> 
> ...
> boost::function< void () >
> 	fnN = bind(Fn, g),
> 	fnN-1 = bind(Fn, fnN),
> 	...,
> 	fn1 = bind(Fn, fn2),
> 	fn = bind(Fn, fn1);
> 
> bind(Fn, fn)();

-- 
Martin Bonner
Senior Software Engineer/Team Leader
PI SHURLOK LTD
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