Re: [Boost-users] [phoenix] A simple lambda func as boost::function

Subject: Re: [Boost-users] [phoenix] A simple lambda func as boost::function
From: Michael Caisse (boost_at_[hidden])
Date: 2009-12-14 20:22:57

Richard Vock wrote:
> Hehe, I already tried that and it gives me this handy little
> error message:
> http://pastebin.com/m787325af
>
> Essentially telling me something I don't understand at all
> about boost::phoenix::at not being a function...
>   

Please don't top post.

>   
>> Richard Vock wrote:
>>     
>>> Hi boost gurus,
>>>
>>> after some time and a lot of pain I somehow managed
>>> to work with boost.lambda in a way that actually
>>> outweighs the costs (code elegance versus time spent
>>> compiling it), but I miss some features (like local
>>> variables) I see in that cute phoenix documentation
>>> and a lot of mailing list threads which all seem
>>> to propose using phoenix rather than lambda (and it
>>> indeed looks a lot better).
>>>
>>> But whenever I try to use it, I somehow fail at the
>>> most simple tasks. Take for example this minimalistic
>>> code example here (note the use of #define USE_LAMBDA):
>>> http://pastebin.com/m3f590a01
>>>
>>> Both versions (with and without USE_LAMBDA defined) 
>>>       
> compile
>   
>>> well on the most recent stable g++ compiler, but the
>>> phoenix version does not output anything. Not at all.
>>> Also note, that this exact lambda expression is mentioned
>>> here:
>>> http://tinyurl.com/ybmp2lw
>>> (well, without the << "\n" but that doesn't change the
>>> problem)
>>>
>>> Could someone please enlighten me by telling me what I 
>>>       

This works for me and I think it is what you are after.
Am I missing something? (btw ... notice that the int in
the function sig is by value ... not reference)

--------------------------------

#include <iostream>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/function.hpp>

void my_func( boost::function< void(int) > func )
{
   for( int i=0; i<5; ++i )
   {
      func( i );
   }
}

int main()
{
   using boost::phoenix::arg_names::arg1;

   my_func( (std::cout << arg1 << '\n') );

   return 0;
}

----------------------------------

regards -
michael

-- 
----------------------------------
Michael Caisse
Object Modeling Designs
www.objectmodelingdesigns.com