Why does Ruby have Numeric.new?

a = Numeric.new  # doesn't take an argument

I ca开发者_Python百科n't imagine a use case for this. Can you?

The Class class defines a new instance method. And so the new class method on Numeric is just a holdover from that - it doesn't do anything - think of it as one of those vestigial organs that animals inherit from a distant ancestor - like the appendix on humans.

Note that the subclasses of Numeric such as Fixnum and Float and their kin explictly undefine the new method. I guess they just didn't bother undefining it for Numeric as direct instances of this class never really exist, and it does no harm keeping it around.

Everything in Ruby is an object, even classes. So to not have a constructor for Numeric would mean there is no Numeric class at all!

Take a look at the docs. It's simply a base class. You would never (well, it would be highly unlikely, anyway :)) use it directly.

You will never use numeric class in that fashion. It's the base class to all numeric types in Ruby.

Ruby’s numeric classes form a full numeric tower, providing many kinds of representations of numbers and numerical representations.

Source: Ruby Tips: Numeric Classes