module nf_base_layer

  !! This module provides the abstract base layer type, to be extended by
  !! specific concrete types.

  implicit none

  private
  public :: base_layer

  type, abstract :: base_layer

    !! This type is the base for creating concrete layer instances.
    !! Extend this type when creating other concrete layer types.

    character(:), allocatable :: activation_name

  contains

    procedure(init_interface), deferred :: init

  end type base_layer

  abstract interface
    subroutine init_interface(self, input_shape)
      !! Initialize the internal layer data structures.
      import :: base_layer
      class(base_layer), intent(in out) :: self
        !! Layer instance
      integer, intent(in) :: input_shape(:)
        !! Shape of the input layer, i.e. the layer that precedes
        !! this layer
    end subroutine init_interface
  end interface

end module nf_base_layer