From: Robert Klemme <bob.news@...>
Date: 2004-10-11T20:24:37+09:00
Subject: Re: [Q] case based on object class


"George Moschovitis" <gm@navel.gr> schrieb im Newsbeitrag
news:ckdn7c$2eim$1@ulysses.noc.ntua.gr...
> > I am not sure what you want to do... do you want to separate these
> > things by class and print out the corresponding symbol?
>
> i want to execute different code depending on the klass (Class) object
> given to the method.
>
> > Anyhow, I tried your code and it worked fine for me. I substituted
> > 4 for obj and commented the ...  of course.
>
> the code works, I am wondering if there is a more elegant/efficient
> way to write it.

The OO way is to use a mapping IMHO:

ACTION_MAPPING = {
  Fixnum => lambda { puts "Fixnum" },
  Float  => lambda { puts "Float" },
  String => lambda { puts "String" },
}

def myfunc(klass)
  code = ACTION_MAPPING[klass]
  raise ArgumentError, "Klass not found: #{klass}" unless code
  code.call
end

You can even define a block for the error as default effectively rendering
the method a one liner like this:

ACTION_MAPPING = Hash.new( lambda { raise ArgumentError, "Klass not
found" } ).update(
  Fixnum => lambda { puts "Fixnum" },
  Float  => lambda { puts "Float" },
  String => lambda { puts "String" }
)

def myfunc(klass) ACTION_MAPPING[klass].call end

Kind regards

    robert