RE: [jgrapht-developers] edge ownership

[Barak N. <bar...@us...>]

> What is the reason for the edge ownership exclusivity?  Allowing edges
> to be aliased in more than one graph is generally useful (especially =
if
> they have some additional information associated with them).  And view
> graphs like SubGraph and AsUndirectedGraph implicitly violate the
> ownership rule.

That indeed useful and works well as long as no one implements an Edge =
that
allows setSource() or setTarget(), that can mess up the graph internals. =
On
the other hand, if total immutability of the edges was required as part =
of
the contract of Edge, then we loose much of the advantage of the =
sharing.=20

In order to protect the graph integrity, I have firstly implemented a =
hard
rule that "only the graph creates its edges" to allow it to promise the
source and target could not be modified (externally). That's why in =
previous
versions of Graph there was no addEdge(Edge) method.=20

That proved to be too restrictive, so I relaxed it a bit later, but I =
still
don't have a complete and coherent solution in mind, what will settle =
all
the (seemingly) contradicting requirements.=20

Any ideas?

Barak=20