Why does private is applicable only for instance methods and isn't for the class methods? Not only that, why doesn't private_class_method method make the class methods private?
class Foo
private
def self.private_class_method
puts 'hello from private_class_method'
end
def private_instace_method
puts 'hello from private_instace_method'
end
end
Foo.private_class_method #Ok!
Foo.new.private_instace_method #error: private method `private_instace_method' called for #<Foo:0x000001020873b8>
How about this?
class Foo
private_class_method :private_class_method
def self.private_class_method
puts 'hello from private_class_method'
end
private
def private_instace_method
puts 'hello from private_instace_method'
end
end
Foo.private_class_method #Ok!
Foo.new.private_instace_method #error: private method `private_instace_method' called for #<Foo:0x000001020873b8>
How do I make a class method private?
You can create a private class methods like this:
class Foo
def self.will_be_private
# ...
end
private_class_method :will_be_private
end
Or like this:
class Foo
class << self
private
def will_be_private
# ...
end
end
end
While it is possible the make a class methods private, I can hardly think of a good reason to do so. IMO a private class method is a code smell and indicates that there is a thing that should be extracted into it own class.