Ruby WeakRef類用法及代碼示例

允許引用對象為garbage-collected 的弱引用類。

WeakRef 可以完全像它引用的對象一樣使用。

用法：

foo = Object.new            # create a new object instance
p foo.to_s                  # original's class
foo = WeakRef.new(foo)      # reassign foo with WeakRef instance
p foo.to_s                  # should be same class
GC.start                    # start the garbage collector
p foo.to_s                  # should raise exception (recycled)