Module Global Hash

Ruby
1

#!/usr/bin/env ruby
module Users
class User < Struct.new(:screenname, :password, :dob, :join_date,
:age)
def initialize(sn, pw, dob)
self.screenname = sn
self.password = pw
self.dob = Time.parse(dob)
self.join_date = Time.now
self.age = Time.now.year - Time.parse(dob).year
end
end
#########################################
user_hash = {}

def new(sn, pw, dob)
Users::user_hash[sn] = User.new(sn, pw, dob)
end
#########################################
module_function :new
end

I’m trying to make it so when I call:
Users::new(“screenname”, “pass”, “1/15/91”)

it adds a new instance of the User class into user_hash, but when I
execute the above code in IRB I get a NoMethodError for user_hash for
the Users:module

I’ve also tried putting both a @ and @@ infront of user_hash but irb
comes up with the same error.

2

On Jan 28, 12:06 am, Ryan L. [email protected] wrote:

end

Posted viahttp://www.ruby-forum.com/.
Remember that in Ruby, everything is an object and objects communicate
by passing messages (calling methods). So you can’t get to variables
of an object (such as user_hash). You can only call methods that an
object responds to.

3

On Jan 28, 12:17 am, Wyatt G. [email protected] wrote:

  self.password   = pw

end

I’ve also tried putting both a @ and @@ infront of user_hash but irb
comes up with the same error.

Posted viahttp://www.ruby-forum.com/.

Remember that in Ruby, everything is an object and objects communicate
by passing messages (calling methods). So you can’t get to variables
of an object (such as user_hash). You can only call methods that an
object responds to.

I think what’s going on here is that when the parser gets to the line
that says

user_hash = {}

it looks for a method called user_hash to execute. It doesn’t realize
that you’re trying to instantiate a variable. Maybe you should
consider turning the Users module into a class and trying @@user_hash
= {} again.

4

Wyatt G. wrote:

On Jan 28, 12:17 am, Wyatt G. [email protected] wrote:

  self.password   = pw

end

I’ve also tried putting both a @ and @@ infront of user_hash but irb
comes up with the same error.

Posted viahttp://www.ruby-forum.com/.

Remember that in Ruby, everything is an object and objects communicate
by passing messages (calling methods). So you can’t get to variables
of an object (such as user_hash). You can only call methods that an
object responds to.

I think what’s going on here is that when the parser gets to the line
that says

user_hash = {}

it looks for a method called user_hash to execute. It doesn’t realize
that you’re trying to instantiate a variable. Maybe you should
consider turning the Users module into a class and trying @@user_hash
= {} again.

I thought of this, but I’m going to be using a system with many many
users and each time I would call Users, I would crate two classes,
taking up twice as much memory.

Should I just drop the module and just keep it in a Users.rb file to
call it later?

5

On Jan 28, 2008, at 12:06 AM, Ryan L. wrote:

end

I’m trying to make it so when I call:
Users::new(“screenname”, “pass”, “1/15/91”)

it adds a new instance of the User class into user_hash, but when I
execute the above code in IRB I get a NoMethodError for user_hash for
the Users:module

The way you’ve used it, user_hash is a local variable for the module
Users block. It disappears when the block ends.

You don’t need a separate enclosing module. You’ve already got User.

In the following code, I used an instance variable of User,
@user_hash, to store the instances by name, User#initialize adds the
entry, and for added ease of use, I defined User.[] and User.[]= as a
way to access @user_hash.

require ‘time’
class User < Struct.new(:screenname, :password, :dob, :join_date, :age)

class <<self
def
user_hash[u]
end
def []=(name, struct)
user_hash[name] = struct
end
def user_hash
@user_hash ||= {}
end
end

def initialize(sn, pw, dob)
self.screenname = sn
self.password = pw
self.dob = Time.parse(dob)
self.join_date = Time.now
self.age = Time.now.year - Time.parse(dob).year
self.class[sn] = self
end
end

User.new(‘bob’, ‘pw’, ‘1/1/01’)

p User[‘bob’]
p User.user_hash

6

2008/1/28, Gary W. [email protected]:

On Jan 28, 2008, at 12:06 AM, Ryan L. wrote:

#!/usr/bin/env ruby
module Users
class User < Struct.new(:screenname, :password, :dob, :join_date,
:age)

You do not need to inherit from the new struct class, instead you can do

User = Struct.new(:screenname, :password, :dob, :join_date, :age)
class User
…
end

it adds a new instance of the User class into user_hash, but when I
execute the above code in IRB I get a NoMethodError for user_hash for
the Users:module

Note though that this approach will prevent any User instance from
being garbage collected. This might or might not be what you want. I
do not know the use case but there is another option: you can traverse
all User instances via ObjectSpace.

Ah, and another remark: the implementations show so far will also
allow to create two users with the same name but only one of them will
be accessible via the Hash.

Kind regards

robert

7

On Jan 28, 2008, at 4:18 AM, Robert K. wrote:

can do

User = Struct.new(:screenname, :password, :dob, :join_date, :age)
class User
…
end

I like:

User = Struct.new(…) do

end

James Edward G. II

8

Gary W. wrote:

class <<self

Hey, thanks man. I was thinking about defining [] and []=, but I didnt
know about <<self.

9

2008/1/28, James G. [email protected]:

User = Struct.new(…) do

Of course. Unfortunately it does not work with class constants
properly. I should have mentioned that. (In my experiments I wanted
to use User::USERS.)

Thanks for pointing it out!

Kind regards

robert