Is it possible to alias an attr_reader method in Ruby? I have a class with a favourites property that I want to alias to favorites for American users. What's the idiomatic Ruby way to do this?
views:
227answers:
2
+9
A:
Yes, you can just use the alias method. A very scrappy example:
class X
attr_accessor :favourites
alias :favorites :favourites
end
Peter Cooper
2010-01-16 18:50:15
Yet still a great one!
Doug Neiner
2010-01-16 18:50:58
Thanks Peter. Is there any reason to prefer `alias` to `alias_method`?
John Topley
2010-01-16 19:05:29
`alias` is a keyword and therefore a little more low-level than `alias_method`. `alias` will resolve methods statically, while `alias_method` does depend on the current `self`. See http://www.ruby-forum.com/topic/135598#604485 (but for your use case, it makes no difference)
levinalex
2010-01-16 19:09:30
For this example is pretty much the same thing. alias and alias_method within a class defenition do the same thing given that the methods you are trying to alias are instance methods. If you use alias outside a class definition, lets say inside a instance_eval, your 'aliasing' a method of self, thus creating a singleton method for that object. If self happens to be a class then you're 'aliasing' a instance method to a singleton method of the class, which as you might have guess is in fact a class method.
pgmura
2010-01-16 19:34:28
+4
A:
attr_reader simply generates appropriate instance methods. This:
class Foo
attr_reader :bar
end
is identical to:
class Foo
def bar
@bar
end
end
therefore, alias_method works as you'd expect it to:
class Foo
attr_reader :favourites
alias_method :favorites, :favourites
# and if you also need to provide writers
attr_writer :favourites
alias_method :favorites=, :favourites=
end
levinalex
2010-01-16 18:53:42