11.3-OLD Graph example

In this section, we show a further example on using virtual class attributes from the domain of graphs.

Quite incomplete
We should make displayable an orthogonal property of graph, men måske ikke nødvendig for eksemplet?
But Network should be completed

Beta book:
class Graph:
   class Node:< ...
   class Link:< ...
   root: ref Node
   connect:< ...
class DisplayableGraph: Graph
   class DisplaySymbol:< ??
   class DisplayLine:< ??
   class Node ::< { dispSymbol: ref DisplaySymbol }
   class Link ::< { dispLine: ref DisplayLine }
   connect ::< ...
   display:< ...
class TravelingSalesmanGraph: Graph
   class Node ::< { name: ref text }
   class Link ::< { distance: var integer }
   connect ::< { ... }

Pipe graph
Internet: Nodes/Servere, links, …, kabler, WIFI

class Network: Graph
   class Node::<  what do we have in a node? Mapping: host -> link
         -- receivePacket, sendPacket, ...
      ...
   class Link::<  -- capacity/speed of connection
      ...

Page 5.x: -- almost the same as TravelingSalesmanGraph above
class Graph:
   class Node:<
      firstEdge: ref Edge
      insertEdgeTo(to: ref Node)-> ref Edge:
         ...
      display:< ...

   class Edge:<
      from, to: ref Node
      nextEdge: ref Edge;
      deleteMe:<
      display:<
         inner(display)

class RoadAndCityGraph: Graph 
   class Node::< 
      cityName: ref String
      ...
      display::
         ... name of the city

      firstEdge.roadLength  

   class Edge::<
      roadLength: var Integer
      ...
      display::
         ... length of the road

      from.cityName