[E-Lang] Thoughts on Persistence in E.

[Dean Tribble]

> >0) I can serialize anything without an error being spit out.
>
>Yes, I tentatively made a strange decision here.  If I encounter something
>that's not serializable, I serialize a broken reference rather than throwing
>an exception.  This was, a bad subgraph cannot prevent the persistence and
>revival of the overall graph.  I feel very uncertain about this decision,
>and it's certainly worth arguing about.

Use a keeper.  The serialization process calls an object supplied by the 
creator which implements the error policy.  Recording the error for the 
caller and then continuing becomes a trivial improvement over the 
swallow-the-error approach.

>For the corresponding issue in CapTP I made opposite decision: I throw an
>exception, causing the serialization to fail.

Also the same mechanism as above but with a different keeper.