From: Austin Ziegler <austin@...>
Date: 2002-12-24T23:42:06+09:00
Subject: Re: Hash#update

On Tue, 24 Dec 2002 11:47:36 +0900, Yukihiro Matsumoto wrote:
> In message "Re: Hash#update" on 02/12/23, Austin Ziegler
> <austin@halostatue.ca> writes:
>|> No information lost by String#+ or Array#+, but Hash#update may
>|> lose the value. That's why I rejected the name "+". It is
>|> possible to provide the non destructive "update" under different
>|> name. Good name?
>| Hash#union, also Hash#| (not Hash#^).
> Is it OK for you to lose values by the "union" method? Not for me.

Actually, it is. Union -- as in a set union -- only keeps one
instance of the key. In this instance, I would expect that:

h1 = { 1 => 2, 2 => 3, 3 => 4 }
h2 = { 1 => 5, 4 => 6, 3 => 7 }
h3 = h1 | h2 # { 1 => 5, 2 => 3, 3 => 7, 4 => 6 }
h4 = h2 | h1 # { 1 => 2, 2 => 3, 3 => 4, 4 => 6 }

I would definitely NOT expect loss of values in "+" or "union all"
(to use the SQL term).

-austin
-- Austin Ziegler, austin@halostatue.ca on 2002.12.24 at 09.40.12