From: ptkwt@... (Phil Tomson)
Date: 2004-04-10T02:24:18+09:00
Subject: Re: Would a ':=' operator break anything?

In article <4076AA59.4020507@hypermetrics.com>,
Hal Fulton  <hal9000@hypermetrics.com> wrote:
>Yukihiro Matsumoto wrote:
>
>> |So how about it, would allowing a ':=' operator break anything?
>> 
>> The point is what you want is not assignment in Ruby.  It might cause
>> confusion that naming ":=" something which is not an assignment.
>> Besides that, I may use ":=" for something different in the future,
>> although I have no plan now (I had thought to use it once).
>
>I think I see his point, however. I will make these comments:
>
>1. I view his := as a kind of limited assignment.
>
>2. It would fully change the state of the object, but would not
>    change the class or object id.
>

exactly.

>3. In that sense, it would be like a synonym for #replace on Arrays
>    and Strings:
>          str := "hello"    # same as str.replace("hello")
>          arr := [1,2,3]    # ...
>
>4. Of course, this is problematic for Fixnums (etc.), as they are
>    immediate values and are not mutable.

Finxnums (and other immediates) wouldn't have to implement ':=' - actually 
no class would have to implement it, it would be around in case people 
want to override it in their own classes.

But, as someone mentioned in this thread '<<' could be used for this 
purpose.  So maybe that's the way to go.


Phil