Object to which a meta class belongs?

[Erik Veenstra]

If a singleton class belongs to an object, it should be
possible to determine to which object it belongs. Is that
possible?

I came up with the code below, but it might not be very fast.

Thanks.

gegroet,
Erik V. - http://www.erikveen.dds.nl/

----------------------------------------------------------------

class Object
def metaclass
obj = self

class << self
self
end.instance_eval do
instance_eval <<-END
def belongs_to
ObjectSpace._id2ref(#{obj.__id__})
end
END

self
end
end
end

a = "TEST"

p a.__id__
p a.metaclass.belongs_to.__id__

----------------------------------------------------------------

 

[Sean O'Halpin]

If a singleton class belongs to an object, it should be
possible to determine to which object it belongs. Is that
possible?

I came up with the code below, but it might not be very fast.

Thanks.

gegroet,
Erik V. - http://www.erikveen.dds.nl/

----------------------------------------------------------------

class Object
def metaclass
obj = self

class << self
self
end.instance_eval do
instance_eval <<-END
def belongs_to
ObjectSpace._id2ref(#{obj.__id__})
end
END

self
end
end
end

a = "TEST"

p a.__id__
p a.metaclass.belongs_to.__id__

How about this?

class Object
def singleton_of
ObjectSpace.each_object(self) do |obj|
return obj
end
end
end

Regards,
Sean

 

[Erik Veenstra]

It does work work, but...

... It's even slower. Much slower. ;]

Thanks.

gegroet,
Erik V. - http://www.erikveen.dds.nl/

----------------------------------------------------------------

CPU ELAPSED COUNT CPU/COUNT LABEL
5.850000 6.708499 1 5.850000 :singleton_of
0.560000 1.097820 1 0.560000 :belongs_to

----------------------------------------------------------------

class Module
def singleton_of
res = nil
ObjectSpace.each_object(self) do |obj|
res = obj
end
res
end
end

----------------------------------------------------------------

 

[Sean O'Halpin]

It does work work, but...

... It's even slower. Much slower. ;]

Thanks.

gegroet,
Erik V. - http://www.erikveen.dds.nl/

Whoops! Knew I should have benchmarked it.
ObjectSpace.each_object really is a sledgehammer...

Regards,
Sean