From: Gavin Kistner <gavin@...>
Date: 2005-06-01T23:00:58+09:00
Subject: Re: Implementing a Read-Only array

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On Jun 1, 2005, at 7:49 AM, Brian Schr=F6der wrote:
> On 01/06/05, Gavin Kistner <gavin@refinery.com> wrote:
>> class ReadOnlyArray < Array
>>      alias_method :'__ro_<<', :'<<' #:nodoc:
>>      alias_method :__ro_insert, :insert #:nodoc:
>>      alias_method :__ro_delete_at, :delete_at #:nodoc:
>>      affectors =3D %w| << []=3D clear concat delete delete_at =
delete_if
>> fill flatten! insert map! pack pop push reject! replace reverse!
>> shift slice! sort! uniq! unshift |
>>      affectors.each{ |name| undef_method name }
>> end
> Why not create a proxy class that contains an array and only forwards
> the reading methods. It seems to me, that this would achieve exactly
> what you want.

That's an interesting idea. What advantage do you think that would =20
offer compared to my implementation above? How would you modify the =20
internal representation when necessary? (Perhaps the constructor for =20
the proxy class receives the array that it is supposed to wrap?)

One advantage of mine versus the proxy approach would be that by =20
actually inheriting from Array, my class supports additional methods =20
defined by the user for Array or Enumerable. (If the user has added a =20=

special Array#my_collect method, my array is extended as well.)

(I think that it's correct that it would not be possible for a custom =20=

user method to modify the array, if I'm undef'ing all core methods =20
for modifying it, yes?)

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