How do I tell the difference between a class C and the singleton class of an instance of C

ruby-talk
1

Suppose that:

class C; end
c = C.new
sing = (class << c; self; end)

If a method is called with C and sing, but I don't know which is first and
which is second in the parameter list, how do I tell them apart?

Thanks,
dean

···

--
Dean Wampler
http://www.objectmentor.com
http://www.aspectprogramming.com
http://aquarium.rubyforge.org

2

I just figured out a way, if I also have the instance "c".

c.instance_of?(C) # => true
c.instance_of?(sing) # => false

Also works for kind_of? and is_a?

Thanks, Dean! :wink:

···

On 11/2/07, Dean Wampler <deanwampler@gmail.com> wrote:

Suppose that:

class C; end
c = C.new
sing = (class << c; self; end)

If a method is called with C and sing, but I don't know which is first and
which is second in the parameter list, how do I tell them apart?

Thanks,
dean

--
Dean Wampler
http://www.objectmentor.com
http://www.aspectprogramming.com
http://aquarium.rubyforge.org
http://www.contract4j.org

--
Dean Wampler
http://www.objectmentor.com
http://www.aspectprogramming.com
http://aquarium.rubyforge.org
http://www.contract4j.org

3

"Dean Wampler" <deanwampler@gmail.com> writes:

Suppose that:

class C; end
c = C.new
sing = (class << c; self; end)

If a method is called with C and sing, but I don't know which is first and
which is second in the parameter list, how do I tell them apart?

C.name ==> "C"
sing.name ==> ""

YS

4

Thanks.

Correction: only instance_of? works. is_a? and kind_a? both return true for
"C" and "sing".

···

On 11/2/07, Yohanes Santoso <ysantoso-rubytalk@dessyku.is-a-geek.org> wrote:

"Dean Wampler" <deanwampler@gmail.com> writes:

> Suppose that:
>
> class C; end
> c = C.new
> sing = (class << c; self; end)
>
> If a method is called with C and sing, but I don't know which is first
and
> which is second in the parameter list, how do I tell them apart?

C.name ==> "C"
sing.name ==> ""

YS

--
Dean Wampler
http://www.objectmentor.com
http://www.aspectprogramming.com
http://aquarium.rubyforge.org
http://www.contract4j.org