[Boost-users] multi_index, best way to do insert_or_replace

From: bert hubert (bert.hubert_at_[hidden])
Date: 2006-04-28 03:11:08

Hi,

I misread (or didn't read) the boost::multi_index_container documentation
and assumed 'insert' on a unique index would do 'replace', but of course it
doesn't and shouldn't.

So, I've made this change:

-         s_negcache.insert(ne);
+
+         pair<negcache_t::iterator, bool> res=s_negcache.insert(ne);
+         if(!res.second) {
+           s_negcache.erase(res.first);
+           s_negcache.insert(ne);
+         }

But I can't help feeling there is probably a better and prettier way. Do
people have any suggestions? 

In this case, ne is a NegCacheEntry, defined as:

struct NegCacheEntry
{
  string d_name;
  QType d_qtype;
  string d_qname;
  uint32_t d_ttd;
};

And the index:

typedef multi_index_container <
  NegCacheEntry,
  indexed_by <
     ordered_unique<
         composite_key<
               NegCacheEntry,
                  member<NegCacheEntry, string, &NegCacheEntry::d_name>,
                  member<NegCacheEntry, QType, &NegCacheEntry::d_qtype>
         >,
         composite_key_compare<CIStringCompare, std::less<QType> >
     >,
     ordered_non_unique<
         member<NegCacheEntry, uint32_t, &NegCacheEntry::d_ttd>
     >
  >
>negcache_t;

Thanks!

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