Object creation with a "variable classname"

Ruby
1

Hi,

I would to know if it is possible to do something like that:

def create_object(class_name)
my_object = class_name.new
end

I tried with class.new(&class_name)

Class_name = Class.new(&class_name)
my_object = Class_name.New

In fact I have a single table inheritence ( yes, I’m doing a Rails app
:wink: ). According to the action the user selects , I want to create the
apropriated object.

My English is very bad but I’ll be very happy if you could help me.

Thanks :slight_smile:

2

cedric.ch wrote:

Hi,

I would to know if it is possible to do something like that:

def create_object(class_name)
my_object = class_name.new
end

I tried with class.new(&class_name)

x = Object.const_get( class_name ).new

–
James B.

“Inside every large system there’s a small system trying to get out”.
- Chet Hendrickson

3

James B. a écrit :

x = Object.const_get( class_name ).new

–
James B.

“Inside every large system there’s a small system trying to get out”.
- Chet Hendrickson

Wow !
Thank you.

4

Wow !
Thank you.

You’re welcome.

Now go help the next person, when you know something they (yet) do not.

–
James B.

http://www.rubyaz.org - Hacking in the Desert
Ruby Code & Style - The Journal By & For Rubyists
http://beginningruby.com - Beginning Ruby: The Online Book
http://www.jamesbritt.com - Playing with Better Toys

5

On Dec 26, 2006, at 6:52 PM, James B. wrote:

cedric.ch wrote:

Hi,
I would to know if it is possible to do something like that:
def create_object(class_name)
my_object = class_name.new
end
I tried with class.new(&class_name)

x = Object.const_get( class_name ).new

Does that still work if there’s a module mentioned in the string with
‘::’ included? I seem to remember a discussion or maybe an
eigenclass blog entry that mentioned the problem. But maybe I’m wrong.
-Mat

6

Mat S. wrote:

x = Object.const_get( class_name ).new

Does that still work if there’s a module mentioned in the string with
‘::’ included? I seem to remember a discussion or maybe an eigenclass
blog entry that mentioned the problem. But maybe I’m wrong.
-Mat

Well, try it and see:

module Foo
class Bar
def baz
warn ‘BAZ!’
end
end
end

Foo::Bar.new.baz

Object.const_get( ‘Foo::Bar’ ).new.baz

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/160468

–
James B.

http://web2.0validator.com - We’re the Dot in Web 2.0
http://www.rubyaz.org - Hacking in the Desert
http://www.jamesbritt.com - Playing with Better Toys

7

On Dec 26, 2006, at 11:46 PM, James B. wrote:

Foo::Bar.new.baz

Object.const_get( ‘Foo::Bar’ ).new.baz

touché… I think :slight_smile:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/160468

Yeah, that’s the conversation I was talking about. Thanks for
digging it up. Your google-fu is more powerful than mine :slight_smile:
-Mat