CODEWITHSUNDEEP
ruby
Jak
Jak

Reputation: 181

How we can overwrite class name of the object.?

How we can overwrite the class name of an object ?

Example: 
$ irb
irb(main):001:0> class Man
irb(main):002:1> end
=> nil
irb(main):003:0> obj = Man.new
=> #<Man:0xb7756464>
irb(main):004:0> puts obj.class
Man
=> nil

I want some thing like that

puts obj.class 
Van instead of Man
 => nil

Upvotes: 1

Views: 259

Answers (3)

Andrew Grimm
Andrew Grimm

Reputation: 81520

I know how to overwrite the apparent class name:

class Man
  def self.inspect
    "Van"
  end
end

irb(main):007:0* m = Man.new
=> #<Man:0x144ace0>
irb(main):008:0> m.class
=> Van

(ActiveRecord does something similar)

But doing a convincing forgery of object inspection is tricky. I don't know how to do the 0xb7756464 bit in #<Man:0xb7756464>, so I don't know how to re-implement Man#inspect.

Upvotes: 0

DigitalRoss
DigitalRoss

Reputation: 146073

class A; end
B = A.clone
o = B.new
p o.class
=> B

Upvotes: 1

Mchl
Mchl

Reputation: 62387

Remeber, that class method does not return a class name (a string), but actually a constant class object. You'd need to create a class Van first, then override obj.class method, so that it returns Van instead of Man

irb(main):001:0> class Man
irb(main):002:1> end
=> nil
irb(main):003:0> class Van
irb(main):004:1> end
=> nil
irb(main):005:0> obj = Man.new
=> #<Man:0x25043b8>
irb(main):006:0> def obj.class
irb(main):007:1>   Van
irb(main):008:1> end
=> nil
irb(main):009:0> obj.class
=> Van

is_a? and other methods might need overriding too

irb(main):010:0> obj.is_a? Man
=> true
irb(main):011:0> obj.is_a? Van
=> false

Upvotes: 0

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