From: Dennis Decker Jensen <dennisdecker@...>
Date: 2001-04-29T02:48:33+09:00
Subject: [ruby-talk:14382] Re: Immutable Arrays?

Johann Hibschman wrote:
| Guy N. Hurst wrote:
|
| > a = [2,3,4]  # array
| > a.freeze     # now immutable
| > a[1] = 0     # TypeError: can't modify frozen array
|
| Thanks.  Would there be anything obviously wrong with:
|
| class Tuple < Array
|   def initialize (values)
|     replace values
|     freeze
|   end
| end
|
| as a "freezer" object?  Or is this just getting silly?
|

Notice the default behaviour for String-keys (Thanks to Dave and Andy for
RI):

--------------------------------------------------------------- Hash#[]=
     hsh[ aKeyObject ] = aValueObject -> aValueObject
------------------------------------------------------------------------
     Element Assignment---Associates the value given by aValueObject
     with the key given by aKeyObject. aKeyObject should not have its
     value changed while it is in use as a key (a String passed as a key
     will be duplicated and frozen).
        h = { "a" => 100, "b" => 200 }
        h["a"] = 9
        h["c"] = 4
        h   #=> {"a"=>9, "b"=>200, "c"=>4}

I think it would be better if Hash#[aKeyObject] always duplicated and froze
aKeyObject no matter what the type of aKeyObject should be. That way you
wouldn't have to worry of side-effects.

Should this become a RCR?

Regards,

Dennis Decker Jensen