The spec's definition of <http://telepathy.freedesktop.org/spec/Account.html#org.freedesktop.Telepathy.Account.ConnectionStatus> is pretty clear about what its value will be in different states. TpQt4's documentation is not. It's not obvious to an API user which method they should use. (I don't really see the point of haveConnection(); is it any easier than checking if connection() returns non-0?)
Before the "industrialization" (factories) work, the first call to connection() after haveConnection had cycled from false to true did expensive initialization constructing the actual proxy etc. Therefore it made sense to have a separate checker. You're right however that it doesn't really make sense anymore - and we have plans to drop it in the API/ABI break (and have just a connectionChanged instead). ++ for suggestion to improve the docs... Will do at ~some point~ in the future.
0.5.0 removes haveConnection() and haveConnectionChanged() completely. The documentation issues still stands, however...
As there is not such methods for a very long time, we have no any reason to document them.
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