BIND 10 #2292: eliminate const_cast from domaintree.h

[BIND 10 Development]

#2292: eliminate const_cast from domaintree.h
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                   Reporter:         |                 Owner:  UnAssigned
  jinmei                             |                Status:  reviewing
                       Type:         |             Milestone:
  defect                             |  Sprint-20121009
                   Priority:         |            Resolution:
  medium                             |             Sensitive:  0
                  Component:  data   |           Sub-Project:  DNS
  source                             |  Estimated Difficulty:  4
                   Keywords:         |           Total Hours:  0
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by jinmei):

 I've not given a full review to yet, but it looks like somewhat
 different from what I originally expected, so let me begin with
 a higher level question.

 For example, I thought we should be able to make `node`
 `const ZoneTableNode*` in `ZoneTable::findZone()` because this node
 should only be used in read-only context.  To do this we'll have to
 change the definition of `ZoneTable::FindResult` so the type of
 `zone_data` will be `const ZoneData*`.  This will probably require
 some adjustments to other interfaces...and, repeating this type of
 propagation of constness, I expected we should eventually be able to
 eliminate the non cost version of `DomainTree::find()` like this:
 {{{#!cpp
     Result find(const isc::dns::Name& name,
                 DomainTreeNode<T>** node) const {
         DomainTreeNodeChain<T> node_path;
         const isc::dns::LabelSequence ls(name);
         return (find<void*>(ls, node, node_path, NULL, NULL));
     }
 }}}

 And, as a result of that, I thought we should be able to kill the
 const_cast naturally.

 Wouldn't it be possible?

-- 
Ticket URL: <http://bind10.isc.org/ticket/2292#comment:4>
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