Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!psuvax1!rutgers!att!cbnewsl!dog
From: dog@cbnewsl.ATT.COM (edward.n.schiebel)
Newsgroups: comp.lang.c++
Subject: Re: coercion of x op= y verses x = x op y ???
Message-ID: <2209@cbnewsl.ATT.COM>
Date: 11 Oct 89 11:44:04 GMT
References: <6590286@hplsla.HP.COM>
Organization: AT&T Bell Laboratories
Lines: 20

From article <6590286@hplsla.HP.COM>, by jima@hplsla.HP.COM (Jim Adcock):
>>In the second case, you are either applying a "*=" operator to an Int (no
>>such operator defined), or to an int (which is generated by a function
>>call, which is not an lvalue).
> 
> In which case, seems to me that coercion oerators should be considered to
> return a reference, so as to be legal in lvalue situations.  Otherwise
> you can't use coercion operators for true polymorphism.  Where is it defined
> whether coercion operators return values or lvalues?  Is there anyway to
> declare which you'd like?

You get to declare the coercion operators, so you decide.  In general,
the operators might not return a reference since the result may be 
computed.  Also, you may not want to allow the coercion operator to
return a reference to private data anyway as this violates data
hiding principles.

	Ed Schiebel
	AT&T Bell Laboratories
	dog@vilya.att.com