Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!tektronix!tekcrl!tekgvs!jans
From: jans@tekgvs.LABS.TEK.COM (Jan Steinman)
Newsgroups: comp.lang.smalltalk
Subject: Re: Polymorphism
Message-ID: <5021@tekgvs.LABS.TEK.COM>
Date: 28 Apr 89 17:32:47 GMT
Organization: Tektronix Inc., Beaverton, Or.
Lines: 20

<<Excuse my ignorance but what is a first-class object?  Does the latter imply 
that there are second-class or n-class objects?>>

<...a first-class object is one that can be stored in a variable, passed as 
parameters, etc...>

I'd say it's a bit more complicated than that.  While it's true that in 
Smalltalk *everything* is an object, knowledge of certain objects is hard-coded 
into the interpreter.  For instance, I don't think you can subclass 
SmallInteger, and you certainly cannot change it's implementation!  There are 
also other, less severe examples: Float can be subclassed, but it's 
implementation cannot be changed (at least not without considerably painful 
interpreter and image hacking).

What Darren was describing as second-class objects (C functions, C function 
pointers, etc.) I prefer to call non-objects.  (1/2 :-)

:::::: Jan Steinman - N7JDB		   Electronic Systems Laboratory ::::::
:::::: jans@tekgvs.LABS.TEK.COM	      Box 500, MS 50-370 (w)503/627-5881 ::::::
:::::: jsteinma@caip.RUTGERS.EDU     Beaverton, OR 97077 (h)503/657-7703 ::::::