Re: [Boost-users] Passing lambda placeholders to functions

Subject: Re: [Boost-users] Passing lambda placeholders to functions
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-06-23 15:52:46

AMDG

Zachary Turner wrote:
> Thanks.  On a related note, if a lambda placeholder refers to a
> structure, is there any way to access its members short of using bind
> and making a fake function to perform the access?
>
> For example
>
> struct foo { int x; int y; };
> struct bar { int x, int y; };
>
> foo f;
>
> options.add_options()
>    ("test", value<bar>()->notifier(
>       var(f.x) = _1.x)));
>
> is what I want.  I've tried a variety of different things, most
> promising seemed to be
>
> options.add_options()
>    ("test", value<bar>()->notifier(
>       var(f.x) = bind(&bar::x, _1)));
>
> but this doesn't work either.
>   

It ought to work.  What's the error?

The following works for me:

#include <boost/lambda/lambda.hpp>
#include <boost/lambda/bind.hpp>
#include <iostream>

struct foo { int x; int y; };
struct bar { int x; int y; };

int main() {
    foo f = { 1, 2 };
    const bar b = { 3, 4 };
    (boost::lambda::var(f.x) = boost::lambda::bind(&bar::x, 
boost::lambda::_1))(b);
    std::cout << f.x << std::endl;
}

In Christ,
Steven Watanabe