CGAL users discussion list

[Mael <>]

Hello,

The simplest to keep your lambda is probably to modify the CGAL function: replacing the instances of ::result_type in linear_interpolation() by

typename boost::result_of<ValueFunctor(typename std::iterator_traits<ForwardIterator>::value_type::first_type)>::type::first_type

will make it work with lambdas as well as more traditional inputs.

I'll make a patch for CGAL to use result_of in the Interpolation package.

Best,
Mael

On 06/14/2018 12:54 PM, Panagiotis Zestanakis wrote:

Dear All, 

Does anyone know any way to directly pass a lambda as a functor to an interpolation function? 

For example, the signature of the linear interpolation function:

template < class ForwardIterator, class Functor>
typename Functor::result_type::first_type
linear_interpolation(ForwardIterator first, ForwardIterator beyond,
                     const typename
                       std::iterator_traits<ForwardIterator>::value_type::
                       second_type& norm,
                     Functor function_value)

requires Functor to provide a type Functor::result_type. This makes it impossible to pass a raw lambda.

Of course one could wrap the lambda with e.g. std::function, but in many cases this is not optimal performance-wise nor style-wise.  

Is there any other way to pass a raw lambda that I am not aware of?

If not, are there any plans to support lambdas in future releases?

Best,

Panos