Path: utzoo!mnetor!uunet!husc6!necntc!rayssd!trr
From: trr@rayssd.ray.com (Terry R. Raymond)
Newsgroups: comp.lang.smalltalk
Subject: Question concerning behavior of assignment and copy methods
Message-ID: <1868@rayssd.ray.com>
Date: 25 Mar 88 23:14:27 GMT
Sender: trr@rayssd.ray.com (Terry R. Raymond @ Raytheon Company, Portsmouth RI)
Organization: Raytheon Company, Portsmouth RI
Lines: 63


I am using Smalltalk/V and would like to know if the following
methods behave the same way in Smalltalk-80.  The methods of
concern are; assignment, shallowCopy and deepCopy.  The expressions
below demonstrate their behavior.  Would somebody who uses
Smalltalk-80 please inform me if the methods behave the same way in
Smalltalk-80.  The expressions were evaluated with "Show it".

Assignment

| a b |
a := #(23 45 78).
b := a.
b at: 1 put: 93.
^a  

The result was  (93 45 78).

Shallow copy

| a b |
a := #(23 45 78).
b := a shallowCopy.
b at: 1 put: 93.
^a

The result was (23 45 78).

| a b |
a := #(23 (45 56) 78).
b := a shallowCopy.
(b at: 2) at: 1 put: 93.
^a
   
The result was (23 (93 56) 78).


Deep Copy

The first example was the same as shallowCopy.

| a b |
a := #(23 (45 56) 78).
b := a deepCopy.
(b at: 2) at: 1 put: 93.
^a
 
The result was (23 (45 56) 78).

| a b |
a := #(23 (45 (56 78) 91) 84).
b := a deepCopy.
((b at: 2) at: 2) at: 1 put: 99.
^a
 
The result was (23 (45 (99 78) 91) 84).


-- 
Terry Raymond
Raytheon Submarine Signal Division; Portsmouth RI; (401)-847-8000 x5597
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