How to return an unmodifiable but nor frozen array?


#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
@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