From: Ryan Davis <ryand-ruby@...>
Date: 2010-10-26T18:24:35+09:00
Subject: Re: why "::", not "."


On Oct 26, 2010, at 01:48 , Oleg Igor wrote:

> Why does the method of modules use a dot, and the constants a double
> colon?
> e.g.
> Math::PI and Math.cos

For the same reason why inner-classes/modules use double colon, because they're constants and that's how you look up via constant namespace.

Math::PI and ActiveRecord::Base are the same type of lookup... it is just that Base is a module and PI is a float.

You can also use double-colon for invocation:

% ruby -e 'p Math::exp(1)'
2.71828182845905

but that is frowned upon as non-idiomatic ruby.