Path: utzoo!news-server.csri.toronto.edu!rutgers!mcnc!nowhere!rick
From: rick@cua.cary.ibm.com (Rick DeNatale)
Newsgroups: comp.lang.smalltalk
Subject: Re: PP Smalltalk R4 Query, Bug?
Message-ID: <1991Mar11.170449.1386@cua.cary.ibm.com>
Date: 11 Mar 91 17:04:49 GMT
References: <4931@goanna.cs.rmit.oz.au> <1991Mar8.140425.10863@m.cs.uiuc.edu>
Sender: rick@cua.cary.ibm.com
Reply-To: rick@cua.cary.ibm.com.UUCP (Rick DeNatale)
Organization: cua
Lines: 28

In article <1991Mar8.140425.10863@m.cs.uiuc.edu> johnson@cs.uiuc.EDU 
(Ralph Johnson) writes:

>These expressions have always been different, because
>the add: messages for collections always returns the
>argument, not the receiver.  Lot of people think that
>this is a design bug, but there *is* a reason for it.
>
>The reason is because of cascaded messaged.
>	aCollection add: thing1;
>		    add: thing2;
>		    add: thing3
>will only work if add: returns the receiver.
>

I don't believe that cascading would work any differently if add: answered
the receiver or not.  (Actually it answers the argument, not the receiver).
Cascading sends the message to the receiver of the previous message regardless
of the answer of that message.

The real reason (at least in my mind) that add: answers the argument is 
because it follows the model of at:put:, which returns its argument so
you can write code like:

         value := aDictionary at: someKey
                     ifAbsent: [ aDictionary at: someKey put: someValue]

Rick DeNatale