Re: [Boost-users] Using lambda to count elements in list of lists

From: Thorsten Ottosen (tottosen_at_[hidden])
Date: 2006-02-01 05:04:05

Daniel Lidström wrote:
> Hello!
> 
> I'm trying to use Boost.Lambda to count the total number of elements
> in a list of lists. This example shows what I'm trying to do:
> 
> #include <boost/lambda/lambda.hpp>
> #include <algorithm>
> #include <list>
> 
> using namespace std;
> using namespace boost::lambda;
> 
> int main()
> {
>    int count = 0;
>    list<list<int> > ll;
>    for_each(ll.begin(), ll.end(), var(count)+=(_1).size());
> }
> 
> This will not compile: (13): error C2039: 'size': is not a member of
> 'boost::lambda::lambda_functor<T>'
> Is this possible to do?

AFAICT, no. Not unless the type of _1 implements all possible member 
functions in the world :-)

This is the single biggest problem of a non-langauage solution to lambdas.

-Thorsten