On Nov 7, 12:50 am, James French <James.Fre...@[...].com> 
wrote:
> 
>  Is there any way of providing read only access to an array? [...]
> 
> 
>  a = A.new
>  a.addDependency("foo")
>  a.dependencies << "bar" # encapsulation subverted

Ask yourself if it's really necessary to implement #dependencies.
(The answer may be 'yes'; I'm just saying don't assume it is.)

For instance, you could provide access to the dependencies like this

  class A
    # initialise and add_dependency as before

    include Enumerable
    def each(&block); @dependencies.each(&block); end

    def [](n)
      @dependencies[n]     # possibly .dup this
    end
  end

  a = A.new
  a.add_dependency "foo"
  a.each do ... end
  a.map { ... }
  a.grep(...)
  a[5]

I've often found, when wrapping a basic data type, that I don't need
access to the 'guts' of that type; I only need to do a certain set of
things, so I implement them and leave it at that.

--
Gavin Sinclair