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From: hopper@ux.acs.umn.edu (hopper)
Newsgroups: comp.std.c++
Subject: Re: the most dissatisfying part of c++
Message-ID: <1923@ux.acs.umn.edu>
Date: 31 Jul 90 22:49:36 GMT
References: <27634@netnews.upenn.edu> <10599@batcomputer.tn.cornell.edu>
Reply-To: hopper@ux.acs.umn.edu (Eric Hopper)
Organization: Omnifarious Software
Lines: 57

In article <10599@batcomputer.tn.cornell.edu> lijewski@tcgould.tn.cornell.edu (Mike Lijewski) writes:
>In article <27634@netnews.upenn.edu> limsoon@saul.cis.upenn.edu.UUCP (Limsoon Wong) writes:
> 
>>the program below is a contrived one.   it cannot  be compiled.
>>the reason is a type fault. however, it exhibits a very central
>>characteristic of update.    something should be  done to allow
>>this kinds of programs.	   			    ---limsoon.
>
>I disagree completely that such programs should be allowed.  Since test()
>returns a `a&', basically what you are asking is that there be a implicit
>conversion from a base class to a derived class.  No way should this be
>allowed.  If you really want the below program to work, one possibility
>would be to add the following constructor definitions to the class
>declaration of b:
>
>	 b() {};
>	 b(a) {};

	I propose that there should be a generic class declaration for a
method that returns the same type as the class which it is part of.

Example:

class A {
   me &func(...); // This function modifies a.
   // .
   // .
   // .  (More stuff)
};

class B : A {
   // .
   // .
   // .  (Even more junk)
};

main()
{
   B b;

   b = b.func();
}

	Of course calling it me isn't neccesarily a good idea, but there
still should be one.

(I believe this is what Mike Lijewski had in mind all along, but I'm not
sure.)

Have fun,
UUCP: rutgers!umn-cs!ux.acs.umn.edu!hopper   (Eric Hopper)
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