null_visitor :: Boost.Graph Documentation

# null_visitor

A no-op event visitor that does nothing. Useful as a placeholder or default when an algorithm requires a visitor but no action is needed, or to fill an unused slot when combining event visitors.

Defined in: `<boost/graph/visitors.hpp>`
Models: EventVisitor

## Synopsis

    struct null_visitor {
      typedef on_no_event event_filter;

      template <class T, class Graph>
      void operator()(T x, Graph& g);
    };

## Associated Types

Type | Description
--- | ---
`event_filter` | `on_no_event`. The visitor is not associated with any algorithm event.

## Member Functions

Member | Description
--- | ---
`void operator()(T x, Graph& g)` | Does nothing.