I’m afraid your statement, “EVERY object has a singleton class implicitly, no matter what.” is not accurate. Objects have a singleton class created implicitly the first time the singleton class is accessed, but if it is never accessed, there is no singleton class. Hence the equality issue. More specifically, the singleton class for an object is created the first time rb_singleton_class (line 854 in class.c) is called. I used RubyInline to write an example that shows this in action:

require “inline”
class Object
inline do |builder|
builder.c ”
VALUE klass(VALUE object) {
return RBASIC(object)->klass;
}”
end
end

class Point; end

point = Point.new

klass(point).object_id
#=> 3080598
klass(Point.new).object_id
#=> 3080598
def point.spin; end
klass(point).object_id
#=> 3013818

What you say is true for classes, a metaclass is created when the class is defined. This is all as of 1.8.6, I haven’t checked if the specifics of this change in 1.9.

Thanks for reading and your comment. More importantly, thanks for all of your insanely great tools.

I do agree and would enjoy a ruby with a truley open metaobject protocol.