Message-ID:	<36A6E9A6.C8FF45CE@eik.bme.hu>
Date:	Thu, 21 Jan 1999 09:47:35 +0100
From:	"Dr. =?iso-8859-1?Q?Andr=E1s=20S=F3lyom?=" <solyom AT eik DOT bme DOT hu>
Organization:	TU Budapest
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To:	djgpp AT delorie DOT com, Shue-Cheng CHEN <scchen AT ohriki DOT t DOT u-tokyo DOT ac DOT jp>
Subject:	Re: How to implement "They are all Vectors, but different realities?"
References:	<36A68B87 DOT FFBA110C AT ohriki DOT t DOT u-tokyo DOT ac DOT jp>
Reply-To:	djgpp AT delorie DOT com

Shue-Cheng CHEN wrote:

>

...

>     But "Force" and "Velocity" are different physical realities, so
>
>         Force + Velocity   // Wrong
>
> I would like to deploit the common implementation of them to avoid
> duplicating their code, but how should I do to prevent from Force +
> Vector meaningless operation?

I think this can solve your problem:
    put a type variable into Vector whose value differ for Force and Velocity
and check this variable in operator+.
or perhaps this more complicated solution is also working:
    Create a base class Vector and and separate derived classes for Force and
Velocity. These can use the same method for addition inherited from Vector, but
accept only the corresponding quantities.

    Andras

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