Re: [boost] BGL: DistanceMatrix

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-01-16 10:31:06

Thanks; are you going to clarify this in the docs?
----- Original Message -----
From: "Jeremy Siek" <jsiek_at_[hidden]>
To: "boost" <boost_at_[hidden]>
Sent: Wednesday, January 16, 2002 9:54 AM
Subject: Re: [boost] BGL: DistanceMatrix

> On Mon, 14 Jan 2002, David Abrahams wrote:
> david.> johnson_all_pairs_shortest.html refers to DistanceMatrix where it
should
> david.> refer to DistanceMap (I think).
>
> Nope.
>
> david.> In any event DistanceMatrix is not defined anywhere.
>
> Yeah, I was lazy. See below.
>
> BTW, I don't always use the name of the concept for the name of the
> template parameter. For example, the DistanceMap parameter is a
> ReadWritePropertyMap. There are several reasons why I am getting away from
> using the concept name as the name of the parameter:
>
> a) what if you have multiple parameters that model the same concept
> b) what if your parameter needs to model multiple concepts
> c) what if multiple parameters when combined model a concept
> d) what if the requirements for a parameter are more complex than
>   simply stating which concept they model. For example, the DistanceMap
>   has further requirements about the value_type.
>
>
> The DistanceMatrix type would model something like the following
> SimpleMatrixConcept, which one could concept check like this:
>
> function_requires< SimpleMatrixConcept<DistanceMatrix> >
>
>
> template <typename Matrix, typename Index, typename Value>
> struct SimpleMatrixConcept
> {
>   void constraints()
>   {
>     Value& v = A[i][j];
>   }
>   Matrix A;
>   Index i, j;
> };
>
>
> Cheers,
> Jeremy
>
>
> ----------------------------------------------------------------------
>  Jeremy Siek                          http://php.indiana.edu/~jsiek/
>  Ph.D. Student, Indiana Univ. B'ton   email: jsiek_at_[hidden]
>  C++ Booster (http://www.boost.org)   office phone: [phone]
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