Attr_accessor on class variables
attr_accessor
generates accessors for instance variables. Class variables in Ruby are a very different thing, and they are usually not what you want. What you probably want here is a class instance variable. You can use attr_accessor
with class instance variables like so:
class Something
class <<self
attr_accessor :things
end
end
Then you can write Something.things = 12
and it will work.
Just some clarification: class variables won't be accessible using attr_accessor
. It's all about instance variables:
class SomeClass
class << self
attr_accessor :things
end
@things = []
end
because in Ruby, class is an instance of the class "Class" (God, I love to say that) and attr_accessor
sets accessor methods for instance variables.
attr_accessor
defines accessor methods for an instance. If you want class level auto-generated accessors you could use it on the metaclass
class Parent
@things = []
class << self
attr_accessor :things
end
end
Parent.things #=> []
Parent.things << :car
Parent.things #=> [:car]
but note that this creates a class level instance variable not a class variable. This is likely what you want anyway, as class variables behave differently than you might expect when dealing w/ inheritance. See "Class and Instance Variables In Ruby".
This is probably the simplest way.
class Parent
def self.things
@@things ||= []
end
end
Parent.things << :car
p Parent.things