Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!deb
From: deb@svax.cs.cornell.edu (David Baraff)
Newsgroups: comp.lang.c++
Subject: stronger type checking of enums
Message-ID: <25740@cornell.UUCP>
Date: 3 Mar 89 02:46:43 GMT
Sender: nobody@cornell.UUCP
Reply-To: deb@cs.cornell.edu (David Baraff)
Organization: Cornell Univ. CS Dept, Ithaca NY
Lines: 28

I'd like to make a case for stronger type checking of enum's.
In cfront 1.2, the following is legal:

--------------------
enum color { RED, GREEN, BLUE };
enum fruit { APPLE, PEAR };

color foo()
{
	return PEAR;		// I say this should cause a problem
}

--------------------

A 'PEAR' is of type 'fruit', and not of type 'COLOR', so
the above definition of foo should be an error (or at the
very least, a warning).

I had a function that was of type 'boolean', but accidentally
returned some other enum constant.
With strong(er) type checking the compiler could easily
have determined I had a type error.

Why shouldn't enum's have their own type, and why shouldn't
the compiler strongly type enum expressions?

	David Baraff
	deb@svax.cs.cornell.edu