From: Minero Aoki <aamine@...>
Date: 2001-04-23T21:44:55+09:00
Subject: [ruby-talk:14074] Re: RCR: getClassFromString method


  In mail "[ruby-talk:14059] Re: RCR: getClassFromString method"
    Marko Schulz <in6x059@public.uni-hamburg.de> wrote:

> > [ Getting a Class by its name as String ]
> 
> You could simply use an eval:

You could use also Module#const_get
(because class name is a constant in Ruby).

    def str2class( name )
      mod = Object
      name.split('::').each {|n| mod = mod.const_get(n) }
      mod
    end

more correctly say:

    def str2class( name )
      m = /\A(?:::)?([A-Z]\w*(?:::[A-Z]\w*)*)\z/.match(name) or
              raise ArgumentError, "illegal constant name: #{name}"
      mod = Object
      m[1].split('::').each {|n| mod = mod.const_get(n) }
      mod
    end

If you use ruby 1.7:

    def str2class( name )
      m = /\A(?:::)?([A-Z]\w*(?:::[A-Z]\w*)*)\z/.match(name) or
              raise ArgumentError, "illegal constant name: #{name}"
      m[1].split('::').inject( Object ) {|mod,n| mod = mod.const_get(n) }
    end

Minero Aoki