Re: [boost] lamda question

28 Jul 2006

      Because you're passing a function pointer to bind() - but you didn't say
which version of print_template you want to pass... I think you run into the
same ambiguity with overloaded functions.

-----Original Message-----
From: Joe Van Dyk [mailto:joevandyk@gmail.com] 
Sent: Friday, July 28, 2006 11:23 AM
To: boost@lists.boost.org
Subject: Re: [boost] lamda question

On 7/27/06, Joe Van Dyk <joevandyk@gmail.com> wrote:
...
On 7/27/06, Kevin Spinar <spinarkm@gmail.com> wrote:
...
On 7/27/06, Joe Van Dyk <joevandyk@gmail.com> wrote:
...
I have Boost 1.33.1 installed.  I'm trying to use Boost.Lamda.
I included all the headers mentioned in the documentation as an
attempt to fix the compile error.
#include <boost/lambda/lambda.hpp>
[snip unneeded includes]
#include <algorithm>
...
#include <list>
int main()
{
   using namespace std;
   using boost::lambda;
list<int> v(10);
   for_each(v.begin(), v.end(), _1 = 1);
}
% g++ lambda.cpp
you should compile with -W -Wall -pedantic -ansi at a minimum.
...
lambda.cpp: In function `int main()':
lambda.cpp:20: error: `_1' undeclared (first use this function)
lambda.cpp:20: error: (Each undeclared identifier is reported only
once for
   each function it appears in.)
Using gcc 3.3.1.
Consider upgrading to gcc 4.  With gcc 4, I get:
error: namespace 'boost::lambda' not allowed in using-declaration
Ah, thanks.  I needed
using namespace boost::lambda;
Joe
Another one:

#include <iostream>
#include <functional>
#include <list>
#include <algorithm>
#include <boost/lambda/lambda.hpp>
#include <boost/lambda/bind.hpp>

using namespace std;

template<class T> void print_template(const T& value)
{
   cout << "value: " << value << endl;
}

void print(const int& value)
{
   cout << "value: " << value << endl;
}

int main()
{
   using namespace boost::lambda;

   list<int> v;
   v.push_back(3);
   v.push_back(4);
   v.push_back(5);
   for_each(v.begin(), v.end(), bind(print, _1));  // Works

   // Why doesn't this work?
   // for_each(v.begin(), v.end(), bind(print_template, _1));
}
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Re: [boost] lamda question

Michael Nicolella