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From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-07-06 06:28:06

Martin Bonner wrote:

> I think specializing std::less<> for types that don't have a natural
> order is /exactly/ the right way to enable such types to be stored in
> an associative container.

map<K, V> will work when you have less<K>, but

    map< pair<K, int>, V >
    map< pair<K, K>, V >
    map< vector<K>, V >

will not.

> The algorithms are a different case. sort doesn't make sense for a
> type that doesn't have a natural order, and in that case the user
> needs to provide an appropriate comparison.

The combination of sort and lower_bound makes sense as a map replacement,
although specifying less<K>() here isn't hard.

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