Accessing a class's constants
Ruby on-RailsRubyConstantsRuby on-Rails Problem Overview
When I have the following:
class Foo
CONSTANT_NAME = ["a", "b", "c"]
...
end
Is there a way to access with Foo::CONSTANT_NAME or do I have to make a class method to access the value?
Ruby on-Rails Solutions
Solution 1 - Ruby on-Rails
What you posted should work perfectly:
class Foo
CONSTANT_NAME = ["a", "b", "c"]
end
Foo::CONSTANT_NAME
# => ["a", "b", "c"]
Solution 2 - Ruby on-Rails
If you're writing additional code within your class that contains the constant, you can treat it like a global.
class Foo
MY_CONSTANT = "hello"
def bar
MY_CONSTANT
end
end
Foo.new.bar #=> hello
If you're accessing the constant outside of the class, prefix it with the class name, followed by two colons
Foo::MY_CONSTANT #=> hello
Solution 3 - Ruby on-Rails
Some alternatives:
class Foo
MY_CONSTANT = "hello"
end
Foo::MY_CONSTANT
# => "hello"
Foo.const_get :MY_CONSTANT
# => "hello"
x = Foo.new
x.class::MY_CONSTANT
# => "hello"
x.class.const_defined? :MY_CONSTANT
# => true
x.class.const_get :MY_CONSTANT
# => "hello"
Solution 4 - Ruby on-Rails
>Is there a way to access Foo::CONSTANT_NAME?
Yes, there is:
Foo::CONSTANT_NAME