def identify_class(obj)
    case obj
    when Hacker,Submission,TestCase,Contest
        puts "It's a #{obj.class}!"
    else
        puts "It's an unknown model"
    end
end

this works incase someone is looking for different solutions.

This problem statement is extremely misleading and needs to be rewritten.

As it is stated, we are lead to believe that Hacker, Submission, TestCase, and Constants are all separate classes inheriting from the same superclass. This means that the following solution should work:

    case obj
    when Hacker, Submission, TestCase, Contest
        puts "It's a #{obj.class}!"
    else
        puts "It's an unknown model"
    end

However, it fails test case 1. Moreover, some of the solutions listed below suggest that Hacker, Submission, TestCase, and Constant are really integer constants euqivalent to to 1, 2, 3, and 4.

Obviously, using integer constants instead of subclasses goes against the problem definition (as currently written). While it will work for basic solutions checking each class type separately, more elaborate solutions taking advantage of the obj.class value will fail. Moreover, testing one solution using subclasses and another using integer constants is extremely misleading; if our solution is expected to work for both situations, the problem statement should explicitly say so.

There is something I can't figure out about the === operator when applied to Classes...

Why does "123".class == String returns true while "123.class === String returns false?

My first idea in this problem was to write

case obj.class

    when Hacker
		
        puts "It's a Hacker!"

etc... But since the === doesn't behave the way I thought it would, I wrote instead

case obj.class.to_s

    when 'Hacker'
		
		    puts "It's a Hacker!"

etc... This way of doing thing seems a little "hacky" to me though... would anyone shed some light on the subtlelties I'm missing?

Why does this work?

case obj

when Hacker, Submission, TestCase, Contest 

    puts "It's a #{obj.class}!"
else 

    puts"It's an unknown model"

end

When "k" == String it says false,

"k" === String is also false

what is the case logic in ruby?

I tried solving this by NOT using the case statement. I did something like this

def identify_class(obj)

if !obj.nil? && ['Hacker', 'Submission', 'TestCase', 'Contest'].include?(obj.class.to_s) puts("It\'s a #{obj.class}!") else puts("It\'s an unknown mode!") end
end

This works for general test case but fails for the hidden one. Any pointers what is causing this failure?