From: Robert Klemme <bob.news@...>
Date: 2005-09-28T16:36:44+09:00
Subject: Re: Dynamically generating classes?

Austin Ziegler wrote:
> On 9/27/05, Jonas Galvez <jonasgalvez@gmail.com> wrote:
>> Jonas Galvez wrote:
>>> Is there anything similar in Ruby? Or do I need to use eval()? Hmm,
>>> apparently:
>>
>> MyClass = Class.new {
>>       attr_accessor :value
>>       def initialize(value)
>>           self.value = value
>>       end
>> }
>>
>> o = MyClass.new(10)
>> puts o.value
>>
>> But now I ask, how do I dynamically set its name ("MyClass") in the
>> global namespace?
>
>   def create_class(name, parent = nil)
>     if parent
>       klass = Class.new(parent)
>     else
>       klass = Class.new
>     end
>     klass.class_eval do
>       def initialize(value)
>         @value = value
>       end
>
>       attr_reader :value
>     end
>
>     Object.const_set(name, klass)
>
>     klass
>   end
>
>   create_class('MyClass')
>   obj = MyClass.new(10)
>   puts obj.value

Note though that this is completely superfluous if you know the name
beforehand:

09:31:38 [Oracle]: ruby -e 'MyClass = Class.new {}; p MyClass.name'
"MyClass"

09:32:48 [Oracle]: ruby -e 'c = Class.new {}; p c.name ; MyClass = c; p
MyClass.name'
""
"MyClass"

Assigning to a constant is sufficient.

Kind regards

    robert