From: Tom Sawyer <transami@...>
Date: 2002-08-12T13:59:29+09:00
Subject: Re: ambiguity between local variable assignment and writter method

well, given that there dosen't seem a reasonable solution to the
ambiguity between local var assignments and standard ruby setter
methods, i am taking kent's advice, and from this day forward will use
something i picked up from rich kilmer. no longer will i use #var=
setter methods!

i'm creating my own attribute module methods to replace attr_reader,
attr_writer, and attr_accessor. instead of having a seperate method for
assignment, i use the same method as the reader, but it checks to see if
there's an argument passed. if there is than it acts like a setter.

not positive about the names of these yet, but:

class Module

  def Module.attr_rw(name)
    name = name.to_s
    class_eval <<-EOS
      if not method_defined?(:#{name})
        def #{name}(*args)
          if args.length > 0
            return @#{name} = args[0]
          else
            if @#{name}
              return @#{name}
            else
              return @#{name} = nil
            end
          end
        end
      end
    EOS
  end
  
  def Module.attr_ro(name)
    name = name.to_s
    class_eval <<-EOS
      if not method_defined?(:#{name})
        def #{name}
          if @#{name}
            return @#{name}
          else
            return @#{name} = nil
          end
        end
      end
    EOS
  end

end

is this the right way to go about this? can anyone improve on this code?
or see any flaws that need to be fixed? i don't have a write only
version, do i really need it? i don't think i've have used one before.

given all is well i can now do:

  class X
    attr_rw :instancevar
    def initialize
      instancevar 'i am me'  # set
      puts instancevar       # get
    end
  end

-- 
~transami