Re: [Boost-users] [Phoenix] Simple if_ issue

Subject: Re: [Boost-users] [Phoenix] Simple if_ issue
From: Nathan Crookston (nathan.crookston_at_[hidden])
Date: 2012-07-02 15:10:16

Aaron,

On Mon, Jul 2, 2012 at 1:05 PM, Nathan Crookston
<nathan.crookston_at_[hidden]> wrote:
> On Mon, Jul 2, 2012 at 12:51 PM,  <Aaron_Wright_at_[hidden]> wrote:
> <snip code>
>> What do I need to do in the second test to get it to compile? Can I tell
>> if_ that its return type is not void?
>
> Sadly no -- this was a point of confusion for me too.  The correct way
> to do this is with if_else

Sorry to reply twice.  The advice is correct, but the link is wrong
(I'm not sure where if_else is documented. . .).  The following shows
usage:

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

namespace px = boost::phoenix;
using px::arg_names::arg1;

int main()
{
  boost::function<std::string(bool)> f = px::if_else(arg1, "true", "false");
  std::cout << f(true) << std::endl;
  std::cout << f(false) << std::endl;
  return 0;
}

HTH,
Nate