class FFI::ManagedStruct

FFI::ManagedStruct allows custom garbage-collection of your FFI::Structs.

The typical use case would be when interacting with a library that has a nontrivial memory management design, such as a linked list or a binary tree.

When the {Struct} instance is garbage collected, FFI::ManagedStruct will invoke the class’s release() method during object finalization.

@example Example usage:

module MyLibrary
  ffi_lib "libmylibrary"
  attach_function :new_dlist, [], :pointer
  attach_function :destroy_dlist, [:pointer], :void
end

class DoublyLinkedList < FFI::ManagedStruct
  @@@
  struct do |s|
    s.name 'struct dlist'
    s.include 'dlist.h'
    s.field :head, :pointer
    s.field :tail, :pointer
  end
  @@@

  def self.release ptr
    MyLibrary.destroy_dlist(ptr)
  end
end

begin
  ptr = DoublyLinkedList.new(MyLibrary.new_dlist)
  #  do something with the list
end
# struct is out of scope, and will be GC'd using DoublyLinkedList#release

@param [Pointer] pointer
Create a new ManagedStruct which will invoke the class method #release on

# File lib/ffi/managedstruct.rb, line 77
def initialize(pointer=nil)
  raise NoMethodError, "release() not implemented for class #{self}" unless self.class.respond_to?(:release, true)
  raise ArgumentError, "Must supply a pointer to memory for the Struct" unless pointer
  super AutoPointer.new(pointer, self.class.method(:release))
end