BIND 10 #2907: add ConfigurableClientList::getZoneTableAccessor method

[BIND 10 Development]

#2907: add ConfigurableClientList::getZoneTableAccessor method
-------------------------------------+-------------------------------------
            Reporter:  jinmei        |                        Owner:
                Type:  task          |  pselkirk
            Priority:  medium        |                       Status:
           Component:  data source   |  reviewing
            Keywords:                |                    Milestone:
           Sensitive:  0             |  Sprint-20130611
         Sub-Project:  DNS           |                   Resolution:
Estimated Difficulty:  3             |                 CVSS Scoring:
         Total Hours:  1.97          |              Defect Severity:  N/A
                                     |  Feature Depending on Ticket:
                                     |  shared memory data source
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Comment (by pselkirk):

 Replying to [comment:16 vorner]:
 > I made one small change to that (please pull) ‒ while it compiled in
 this instance, there's quite substantial change between `X &` and `const X
 &`.
 >
 > The second is „safe“ for the caller, as it won't modify anything and a
 result of expression can be passed, not in the first case, where a real
 variable (well, l-value) is needed and it may change.

 Thanks for clarifying that.

 > I think it may be merged now.

 Thanks, I'll do that momentarily.

 > > > So, is the zone table accessor needed only when configuring it, or
 is it needed during general server handling?
 > >
 > > This is the crucial question, isn't it? I can only guess at intent.
 >
 > Well, it's this is the question that determines if there should be the
 virtual method in the base class. It seems I'm not the only one missing
 the big picture of the changes :-|. But I don't know what to do about
 that.

 I confirmed with Jinmei that `getZoneTableAccessor` is to be a pure
 virtual method in the base class, so to be used during general server
 operation.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2907#comment:17>
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