Newsgroups: comp.lang.c++
Path: utzoo!censor!geac!alias!earth!rae
From: Reid Ellis <rae@gpu.utcs.toronto.edu>
Subject: Re: friend operator +(l,r) vs. operator +(r)
Message-ID: <rae.659682898@earth>
Sender: Reid Ellis <rae%alias@csri.toronto.edu>
Reply-To: Reid Ellis <rae@gpu.utcs.toronto.edu>
Organization: Alias Research, Inc. Toronto ON Canada
References: <11759@hubcap.clemson.edu> <1990Nov21.053431.22340@actrix.co.nz> <1990Nov22.230835.26713@clear.com>
Date: 27 Nov 90 05:14:58 GMT

rmartin@clear.com (Bob Martin) writes:
!foo fa,fb;
!int ia;
!...
!fb=ia+fa;  // adding an int to a foo.
!
!If you use the foo::operator+(foo&) method, then the above statement
!will produce a compiler error since foo::operator+(foo&) requires that
!the left hand side of the + operator must be a foo.

Not necessarily.  What if there existed "foo::operator int()" as well
as "foo:foo(int)"?  Then the above would work fine.

[Personal opinion follows]

	I don't agree with the idea that the result of adding two
	objects of different type should return any arbitrary type, as
	defined by a global function "operator+(type1, type2)".
	Rather, I have a "gut feel" that if I add an orange to an
	apple, it is up to the apple to decide what to do with it.  I
	guess this comes from English where, for example, you add an
	element to a set [resulting in a new set] but you don't add a
	set to an element..

	Does anyone else think that

		operator+(const type1 &, const type2 &);

	should have a return type of type1 at all times?

[end opinion]

					Reid

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