I was reading the Sequel's docs and I'm got curious about the technique used in the following code snippet:
class Post < Sequel::Model(:my_posts)
(...)
end
The Sequel::Model(:my_posts) sets the database table for the model. I'm curious specifically about the parenthesis in Model(:my_posts). I like this interface, but how can I achieve that? It's a bit weird... Seems like the Model can be called as a method... Which is this technique? Can somebody give me an example?
Normally when you use :: with module or class, ruby will try to find expression after :: in constants.
Example::First => as constant
Example::First() => as method
Run this code:
module Example
class << self
def First(a)
puts a
end
end
module First
end
end
Usage:
Example::First(1) # => prints 1
When you use class << self you open self's class so that methods can be redefined for the current self object (which inside a class or module body is the class or module itself). Read good question/answers on SO.
It's good practice, while not mandatory, to start the method name with a lower-case character, because names that start with capital letters are constants in Ruby. It's still possible to use a constant name for a method, but you won't be able to invoke it without parentheses, because the interpeter will look-up for the name as a constant