From: Nasir Khan <rubylearner@...>
Date: 2007-04-04T00:39:19+09:00
Subject: Re: Find the fully qualified name of a class from a string

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Good. This is better.

Thanks
~nasir

On 4/2/07, Rick DeNatale <rick.denatale@gmail.com> wrote:
>
> On 3/31/07, Nasir Khan <rubylearner@gmail.com> wrote:
> > Here is an abridged (out of context) version of my original solution.
> (which
> > I am using now)
> > -----
> > nasir@sparkle:misc>cat find_class_name.rb
> >
> > module EmptyModule
> >    def EmptyModule.clear_all
> >     constants.each {|x| remove_const(x.to_sym)}
> >    end
> > end
> >
> > @my_classes = []
> >
> > def class_from_string(str)
> >   EmptyModule.clear_all  # clean the slate
> >   EmptyModule.module_eval(str)
> > end
> >
> > cstr = <<EOF
> > module B
> >   class A
> >     def a
> >       puts "hello"
> >     end
> >   end
> > end
> > module B
> >   class C
> >   end
> >   class D
> >   end
> > end
> > EOF
> >
> > # This string will usually come from some external invocation of this
> > function
> >
> > class_from_string(cstr)
> >
> >
> > def find_class mod
> >   mod.constants.each do |str|
> >     m = mod.const_get(str)
> >     if m.class == Module
> >       find_class(m)
> >     else
> >       cname = m.to_s
> >       cname = cname.match(/EmptyModule::/).post_match
> >       @my_classes << cname
> >     end
> >   end
> > end
> >
> >
> > find_class( EmptyModule )
> > puts @my_classes.uniq
> >
> > ---------------
> >
> > And the result -
> >
> > nasir@sparkle:misc>ruby find_class_name.rb
> > B::D
> > B::C
> > B::A
> >
> > ----------------
> >
> > I guess I will stick with this solution. set_trace_func usage is very
> > interesting but as I could have potentially several such evaluations
> going
> > on in parallel, I would go with the solution above.
> >
> > Comments criticisms welcome.
>
> This is still not thread safe since if you are doing this on two
> different threads they are sharing the EmptyModule.
>
> Here's my variation using your approach but with an anonymous module
> to do the module_eval:
>
> rick@frodo:/public/rubyscripts$ cat find_classes2.rb
> class String
>   def all_class_names
>     mod = Module.new
>     mod.module_eval(self)
>     mod.all_class_names
>   end
> end
>
> class Module
>   def all_class_names
>     class_names = []
>     constants.each do |const_name|
>       const = const_get(const_name)
>       case const
>       when Class
>         class_names << const.to_s.split(/::/,2)[1]
>       when Module
>         class_names += const.all_class_names
>       end
>     end
>     class_names.uniq
>   end
> end
>
> cstr = <<EOF
> module B
>   class A
>     def a
>       puts "hello"
>     end
>   end
> end
>
> module B
>   class C
>   end
>   class D
>   end
>
>   NonClassConst = :non_class_const
> end
> EOF
>
> puts cstr.all_class_names
> rick@frodo:/public/rubyscripts$ ruby find_classes2.rb
> B::C
> B::A
> B::D
>
>
>
> --
> Rick DeNatale
>
> My blog on Ruby
> http://talklikeaduck.denhaven2.com/
>
>

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