Lambdas and std::function

Question

I\'m trying to catch up on C++11 and all the great new features. I\'m a bit stuck on lambdas.

Here\'s the code I was able to get to work:

#include &         


        

Answer 1

As has been revealed by other posters, this is a template argument deduction for std::function.

One intuitive way to make the second code snippet work is to add your base type when calling the template function: findMatches.

Another way not mentioned by Xeo is using std::is_convertible:

template
vector findMatches(vector search, function  func)
{
    static_assert(std::is_convertible >::value, "func must be convertible to ...");

    vector tmp;

    for(auto item : search)
    {
        if( func(item) )
        {
            tmp.push_back(item);
        }
    }

    return tmp;
}

It avoids wrapping lamda into std::function, and provides a cleaner error message.