From: Horst Duchene <monora@...>
Date: 2004-10-07T07:04:47+09:00
Subject: Re: Ruby Graph Library -- add a single knode

Ralf M�ller wrote:

> Moin Moin,
> i'm usung the Ruby Graph Library (rgl.sourceforge.net) to scan function
> libraries. If function A is used in function B, i add an edge to the
> Graph from B to A.
> To indicate, that a function isn't used in any other function, i would
> just like to add a single knode without any edge.
> I tried 'add_vertex' but no vertices are shown by dotty.
> 
> Anybody, who can enlight me ?
> 

This is a bug in rgl/dot.rb. If you use the latest CVS-Version (1.4), you
should see isolated nodes. See this sample irb session:
 
irb(main):001:0> require 'rgl/dot'
irb(main):002:0> require 'rgl/adjacency'
irb(main):003:0> dg = RGL::DirectedAdjacencyGraph.new
#<RGL::DirectedAdjacencyGraph:0x402de28c @vertice_dict={},
@edgelist_class=Set>
irb(main):004:0> dg.add_vertex 1
#<Set:0x402d9d54 @store={}>

irb(main):072:0> dg.print_dotted_on
digraph RGL__DirectedAdjacencyGraph {
    label = "RGL__DirectedAdjacencyGraph"
    "1" [
        fontsize = 8,
        label = "1"
    ]

}

# You see the isolated vertex in DOT formatted output. Therefore dotty
should display it also:

irb(main):073:0> dg.dotty

Cheers
Horst