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cookrn/a.rb

Forked from ahoward/a.rb
Last active Aug 29, 2015
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# fork it
#
# make it print all true with only ONE LINE OF CODE
class A
def A.foo
@foo ||= (
if self == A
'42.0'
else
# inherited = :FIXME
# inherited = '42.0'
superclass.foo.dup
end
)
end
def A.foo=(foo)
@foo = foo
end
end
class B < A
end
class C < B
end
p( A.foo == B.foo )
p( A.foo.object_id != B.foo.object_id )
p( B.foo == C.foo )
p( B.foo.object_id != C.foo.object_id )
p( A.foo == C.foo )
p( A.foo.object_id != C.foo.object_id )
A.foo = 1
B.foo = 2
C.foo = 3
p( A.foo != B.foo )
p( B.foo != C.foo )
p( A.foo != C.foo )
module M; end
A.send(:extend, M)
B.send(:extend, M)
C.send(:extend, M)
p( A.foo == 1 )
p( B.foo == 2 )
p( C.foo == 3 )
@ahoward

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@ahoward ahoward commented May 19, 2014

heh https://gist.github.com/cookrn/062173b60884af5b3a42#file-a-rb-L12 is cheating.

the point is that the subclasses in inherit the value from the parent

think 'class inheritable attributes'

@agnellvj

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@agnellvj agnellvj commented May 20, 2014

Is that right then? You just make a copy from the superclass and return it if it isn't the parent class?

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