Re: Introduction to traits (and __traits)

[Joseph Rushton Wakeling]

On 30/08/13 23:06, Ali Çehreli wrote:
How about allSatisfy:
   http://dlang.org/phobos/std_typetuple.html#.allSatisfy

I'll have a look at that, thanks :-)

Here's what I came up with, for now.  It should probably be extended with 
further tests on the characteristics of the various member functions but it 
seems to be sufficient for now:

////////////////////////////////////////////////////////

template isGraph(G)
{
    static if (!__traits(hasMember, G, "directed") ||
               !__traits(hasMember, G, "edge") ||
               !__traits(hasMember, G, "edgeCount") ||
               !__traits(hasMember, G, "vertexCount") ||
               !__traits(hasMember, G, "isEdge") ||
               !__traits(hasMember, G, "edgeID") ||
               !__traits(hasMember, G, "addEdge") ||
               !__traits(hasMember, G, "degreeIn") ||
               !__traits(hasMember, G, "degreeOut") ||
               !__traits(hasMember, G, "incidentEdgesIn") ||
               !__traits(hasMember, G, "incidentEdgesOut") ||
               !__traits(hasMember, G, "neighboursIn") ||
               !__traits(hasMember, G, "neighboursOut"))
    {
        enum bool isGraph = false;
    }
    else static if (!isBoolean!(typeof(G.directed)))
    {
        enum bool isGraph = false;
    }
    else static if (G.directed && (__traits(hasMember, G, "degree") ||
                                   __traits(hasMember, G, "incidentEdges") ||
                                   __traits(hasMember, G, "neighbours")))
    {
        enum bool isGraph = false;
    }
    else static if (!G.directed && (!__traits(hasMember, G, "degree") ||
                                    !__traits(hasMember, G, "incidentEdges") ||
                                    !__traits(hasMember, G, "neighbours")))
    {
        enum bool isGraph = false;
    }
    else
    {
        enum bool isGraph = true;
    }
}

////////////////////////////////////////////////////////