Question

Is it possible to change the class of a Ruby object once it has been instantiated, something like:

class A
end

class B
end

a = A.new
a.class = B

or similar.

(the above code does not run as class is a read only variable)

I know this is not advisable, a bit strange, and not something I plan on doing, but is it possible?

Answer 1

No, this is not possible from within ruby.

It is theoretically possible from within a C extension by changing the klass pointer of the given object, but it should be noted that this will be completely implementation-specific, will not work for immediate types (i.e. you definitely can’t change the class of e.g. a fixnum), and might blow up in various ways.