[I sent this earlier but it appears to have been clipped by some mailer
between here and there, so I'm re-sending it]

I have a couple places in my code that resemble the following:

class NamedObject {
 // etc.
public
  const string& name();
 // etc.
};

class NameCompare {
public:
  bool operator()(const NamedObject& lhs,const NamedObject& rhs)
  { return lhs.name()<rhs.name(); }
};

set<NamedObject,NameCompare> objectSet;

And I want to execute code like this:

string name;
cin >> name;
NamedObject& namedObj=*(objectSet.find(name));

I find that there are only two ways to do this reasonably efficiently.
The first is to make objectSet into a map, with the name being the key
and the value being the NamedObject.  But I find the redundancy
unappealing aesthetically, a waste of memory, and a source of potential
error. The second method of doing this is a really disgusting hack that
only works on classes whose source code and interface I can modify.

string name;
cin >> name;
NamedObject tmpObj;
tmpObj.setName(name);
NamedObject& namedObj=*(objectSet.find(tmpObj));

The only aesthetically pleasing solution I can think of would be to make
find a templated member function of the associative container classes.
In other words:

  template<class KeyComparable> iterator find(const KeyComparable& k);

Then, I could accomplish my goal by merely overloading the function-call
operator in the class NameCompare like so:

class NameCompare {
public:
  bool operator()(const NamedObject& lhs,const NamedObject& rhs)
  { return lhs.name()<rhs.name(); }
  bool operator()(const string& lhs,const NamedObject& rhs)
  { return lhs<rhs.name(); }
  bool operator()(const NamedObject& lhs,const string& rhs)
  { return lhs.name()<rhs; }
};

Is there perchance any other way to accomplish my goal?  If not, I'd
like to propose that find, upper_bound, lower_bound, and equal_range be
made templated member functions of the associative container classes.
--
Ian Haggard || ian@shellus.com (work) || IanHaggard@juno.com (home)
Linux -- "Oh, no, Mr Bill!" || #define employer_opinion !my_opinion


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