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OOFILE includes a general dependency mechanism you can use for your own messaging.
All classes are defined in oofmsg.hpp and oofmsg.cpp.
dbBroadcaster and dbReceiver are mixin classes.
Messages are simple unsigned longs, defined as OOFmsgT. You can define your own constants provided they are greater than OOFmsg_LastUsed.
A more useful base class than dbReceiver is dbSingleListener. It includes nested suspend() and resume() methods which stop it receiving messages but allow a quick resume() to reconnect to the previous dbBroadcaster.
The message system is used extensively to trigger re-sorting, copying relationship join fields, copying the internal caches and other support roles.
Most dbTable methods (eg: newRecord, saveRecord) broadcast a similar-named message if they affect the state of the current selection.
The message OOFmsg_ChangeSelection is triggered by wholescale replacement of the selection, eg: by a search(), or combining selections with union_with.
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