Re: [boost] BGL adjacency list container selectors

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-01-09 12:50:36

----- Original Message -----
From: "Lie-Quan Lee" <llee_at_[hidden]>

> With the current method of selecting component containers in BGL, if you
> want to use your own allocator into component conainers, you define your
> own selector. For example:
>
> struct my_vecS {};
> template <class ValueType>
> struct container_gen<my_vecS, ValueType> {
>    typedef std::vector<ValueType, MyOwnAllocator> type;
> };
>
> This is simpler to users. Right?

Let's look at a more realistic case:

  namespace my_company { namespace my_app {
    ...
    // Oh, I need a graph!
    struct my_vecS {};
    // Damn, need to specialize container_gen before I can declare the
graph!
  }}
  namespace boost {
    template <class ValueType>
    struct container_gen<my_vecS, ValueType> {
      typedef std::vector<ValueType, MyOwnAllocator> type;
    };
  }
  namespace my_company { namespace my_app {
    // declare the graph now
    typedef boost::adjacency_list<my_VecS...
  }}

--- Now, my version: ---

  namespace my_company { namespace my_app {
    ...
    // Oh, I need a graph!
    struct my_vecS {
      template <class ValueType>
      struct apply {
        typedef std::vector<ValueType, MyOwnAllocator> type;
      };
    };
    typedef boost::adjacency_list<my_VecS...
  }}