### Home Classes Methods

### In Files

- lib/ffi/managedstruct.rb

### Parent

FFI::Struct

### Methods

- ::new

### Files

- History.txt
- README.rdoc

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# 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 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

### Public Class Methods

new(pointer) click to toggle source
new

When passed a pointer, create a new ManagedStruct which will invoke the class method release() on

    # File lib/ffi/managedstruct.rb, line 48
    def initialize(pointer=nil)
      raise NoMethodError, "release() not implemented for class #{self}" unless self.class.respond_to? :release
      raise ArgumentError, "Must supply a pointer to memory for the Struct" unless pointer
      super AutoPointer.new(pointer, self.class.method(:release))
    end

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