How to return an unmodifiable but nor frozen array?

ruby-talk
1

Hi,

Is there a mean to obtain an unmodifiable array which is not frozen?

Assume you're implementing a directed graph with adjacency lists. A
node would like to expose it's outgoing edges (to let users enjoy its
enumerability for example) but you would like to ensure that this
array will not be modified. A solution would be to duplicate it and I
know that efficiency should not be my concern, but ...

blambeau

2

You can return the array in a container, this container redirects all
"read" operations to the array and does not redirect any "write" operations.

class ArrayContainer
  def initialize(array)
    @array
  end

  def (idx)
    @array[idx]
  end

  ... and so on
end
    
There is a specialized "delegate" class/module in ruby, using it should
result in better performance than the solution in my ArrayContainer
class.

Mfg

Markus

ยทยทยท

On Thu, Jan 08, 2009 at 10:59:29PM +0900, LAMBEAU Bernard wrote:

Hi,

Is there a mean to obtain an unmodifiable array which is not frozen?

Assume you're implementing a directed graph with adjacency lists. A
node would like to expose it's outgoing edges (to let users enjoy its
enumerability for example) but you would like to ensure that this
array will not be modified. A solution would be to duplicate it and I
know that efficiency should not be my concern, but ...

blambeau