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class method

ObjectSpace.reachable_objects_from

ObjectSpace.reachable_objects_from(obj) → array or nil
MRI specific feature

Return all reachable objects from ‘obj’.

This method returns all reachable objects from ‘obj’.

If ‘obj’ has two or more references to the same object ‘x’, then returned array only includes one ‘x’ object.

If ‘obj’ is a non-markable (non-heap management) object such as true, false, nil, symbols and Fixnums (and Flonum) then it simply returns nil.

If ‘obj’ has references to an internal object, then it returns instances of ObjectSpace::InternalObjectWrapper class. This object contains a reference to an internal object and you can check the type of internal object with ‘type’ method.

If ‘obj’ is instance of ObjectSpace::InternalObjectWrapper class, then this method returns all reachable object from an internal object, which is pointed by ‘obj’.

With this method, you can find memory leaks.

This method is only expected to work except with C Ruby.

Example:

Example
ObjectSpace.reachable_objects_from(['a', 'b', 'c'])
#=> [Array, 'a', 'b', 'c']

ObjectSpace.reachable_objects_from(['a', 'a', 'a'])
#=> [Array, 'a', 'a', 'a'] # all 'a' strings have different object id

ObjectSpace.reachable_objects_from([v = 'a', v, v])
#=> [Array, 'a']

ObjectSpace.reachable_objects_from(1)
#=> nil # 1 is not markable (heap managed) object