I need to override the operator << for one single attribute in my class.
Basically, what I want is allow to push only unique integers to my array attribute.
Here's what I have:
class Player
attr_accessor :moves
def initialize
@moves = []
end
def moves<<(value)
raise Exception if @moves.include?(value)
@moves.push(value)
end
end
Unfortunately, this code doesn't work.
How can I improve that or maybe there are better ways to implement such functionality?
class Player
attr_accessor :moves
def initialize
@moves = []
@moves.define_singleton_method(:<<) do |value|
raise Exception if include?(value)
push(value)
end
end
end
You can add methods only specific to a given object using the Object#define_singleton_method. Ruby is really flexible when it comes to meta programming.
However such tools should be used sparingly. I don't know your specific situation, but you are probably better off not giving direct access to @moves. The best approach might be to define methods in Player that create an indirect and more restrictive interface to the internal representation and give you more control.