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Subject: Re: [boost] A design for geometric objects
From: Simonson, Lucanus J (lucanus.j.simonson_at_[hidden])
Date: 2008-12-05 20:25:41

Mathias wrote:
>Overloading certainly is ad-hoc polymorphism with multiple-dispatch
>based on the static type.
>So yes.
>However, isn't this ambiguous?
>A 90 degree polygon should match all three overloads.

Yes, a single 90 degree polygon should match all three overloads, but two 90 degree polygons can only match the correct operator. Each operator takes two arguments.

is_either_polygon_45_set_type<T1, T2> evaluates to a type only if one or the other or both T1 and T2 are of 45 degree flavor. That means that two 90 degree polygons can't instantiate a function that requires is_either_polgyon_45_set_type on its two arguments. Similarly with is_either_polygon_set_type, only if one of the arguments is of arbitrary angle flavor will the arbitrary angle intersection operator be instantiated.


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