Question

If I create a Struct with an attribute which contains a question mark, any instance of that class will not be able to find that method. For e.g.

    Test = Struct.new(:value, :value?)
    t = Test.new(true,true)
    t.value
      => true
    t.value?
    NoMethodError: undefined method `value?' for #<struct Test value=true, :value?=true> 

Any idea ? I am using Ruby 1.9.3-p286.

Answer 1

Yo’ll have to concede that some method names in Ruby are special. For example, if you defined method

o = Object.new
def o.kokot= n
  return n + 1
end

And call

o.kokot 1
#=> 1

The result will still be 1, not 2 as you might expect. This is peculiarity of = sign in method names. In your case of Structs, question mark seems to have such peculiarity, too, which prevents you from retrieving value by calling:

t.value?

You have to call

t[:value?]

That’s it, have a nice day.