WeakRef

Weak Reference class that allows a referenced object to be garbage-collected.

A WeakRef may be used exactly like the object it references-

Usage:

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)

Example

With help from WeakRef, we can implement our own rudimentary WeakHash class-

We will call it W