From: Ben Nagy <ben@...>
Date: 2006-07-29T02:55:59+09:00
Subject: Re: Howto ? :: Person is a customer

> -----Original Message-----
> From: James Britt [mailto:james.britt@gmail.com]
> Sent: Friday, July 28, 2006 2:22 PM
> To: ruby-talk ML
> Subject: Re: Howto ? :: Person is a customer
>
> Squeak Smalltalk wrote:
> > Hi,
> >
> > Beginner question probably but I do not know how to do it correctly.
> >
> > I will read informations from a file and create an object.
> > During my load I do not know if it is a employe or a customer so I
> > create a person object.
> > After the object is created I will know which type it is.
> >
> > After I know I want to change the type of my object.
>
> "Type"?  What exactly do you mean by 'type'?

If you mean class, you can do this (untested in irb)

class Person
	def self.new( param, data )
		if param==1
			Employee.new(data)
		else
			Customer.new(data)
		end
	end
end

Now Person.new(param, data) will return an Employee or a Customer depending
on the param it is passed. Adjust as needed in terms of inspecting the
input.

I consider this needless trickery, but have used it before because it amuses
me. The other responses have more actual software engineering merit.

Cheers,

ben