[ruby-talk:16627] Re: Class Var question

Thanks, I think this will do the trick! Unfortunately it just brings up more
questions than answers.

How can you define instance variables inside of a class method? Who is self?
The class object. What is the difference between a classes' instance
variables and an object's class variables. I tried the following code and it
failed to execute.

class Bob
	def Bob.test
		attr_reader :test1
		@test1 = 1
	end

	def test2
		p self.class.inspect
		p self.class.test1.inspect
	end
end

Bob.test
bob = Bob.new
bob.test2

produced:

"Bob"
bob.rb:9:in `test2': undefined method `test1' for Bob:Class (NameError)
        from bob.rb:15

Does your code work because it is executing in the context of a class
definition, where self is the class being defined?

Thanks for all your help.

Steve Tuckner :>>

-----Original Message-----
From: [e-mail] [mailto:[e-mail]]
Sent: Monday, June 18, 2001 11:01 PM
To: [e-mail]
Subject: [ruby-talk:16616] Re: Class Var question


Hi,

In message "[ruby-talk:16610] Re: Class Var question"
    on 01/06/19, Steve Tuckner <[e-mail]> writes:

|What I want to do is have some "meta" information about an object's
members.
|So for example if an object has two members: ht and wt, I want to
associated
|with them the names to display if I have an object display module. I would
|like to use the following code to use this capability.

<snip>

Is the following code close to what you want?

----

class Object
  def Object.uservar(name, printname)
    @user_vars ||= {}
    @user_vars[name] =  printname
    attr_reader name
  end
  def Object.uservars
    if defined? @user_vars
      @user_vars
    else
      {}
    end
  end
end
 
class Contact 
  uservar :first_name, "First Name"
  uservar :last_name, "Last Name"

  def initialize(first_name, last_name)
    @first_name = first_name
    @last_name = last_name
  end
end

class Address
  uservar :street, "Street"
  uservar :city, "City"
  uservar :country, "Country"
  uservar :postal_code, "Postal Code"

  def initialize(street, city, country, postal_code)
    @street = street
    @city = city
    @country = country
    @postal_code = postal_code
  end
end

def dump_objects(objects)
  objects.each do |object|
    for k, v in object.type.uservars
      print v, ": ", object.send(k), "\n"
    end
    print "\n"
  end
end

dump_objects([Contact.new("Joe", "Schmo"), Address.new("1212 Penny Lane",
"London", "UK", "4A3B2A")])