Bug #12027: Hash descendants are ignoring custom to_hash method

• Status: Rejected
• Assignee: -
• Target version: -
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[zverok (Victor Shepelev)]

I'm not sure it is not intended, but feels really strange:

class A
  def to_hash
    {foo: 'bar'}
  end
end

class B < Hash
  def to_hash
    {foo: 'bar'}
  end
end

a = A.new
b = B.new

p({**a}) # => {foo: 'bar'}
p({**b}) # => {} -- ooops. Seems "internal" hash state is used
# therefore:
b['test'] = 1
p({**b}) # => wrong argument type String (expected Symbol) (TypeError)

What am I missing here?

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Rejected

Because b.is_a?(Hash) already.
to_hash is the method to pretend to be a Hash.