[mythtv-commits] mythtv commit: r11722 - in trunk by danielk

[mythtv at cvs.mythtv.org]

      Author: danielk
        Date: 2006-11-13 02:58:26 +0000 (Mon, 13 Nov 2006)
New Revision: 11722
   Changeset: http://cvs.mythtv.org/trac/changeset/11722

Modified:

   trunk/mythplugins/mytharchive/mytharchive/archivesettings.h
   trunk/mythplugins/mythcontrols/mythcontrols/mythcontrols.h
   trunk/mythplugins/mythdvd/mythdvd/settings.h
   trunk/mythplugins/mythgallery/mythgallery/gallerysettings.cpp
   trunk/mythplugins/mythgallery/mythgallery/gallerysettings.h
   trunk/mythplugins/mythgame/mythgame/gamesettings.cpp
   trunk/mythplugins/mythgame/mythgame/gamesettings.h
   trunk/mythplugins/mythgame/mythgame/romedit.cpp
   trunk/mythplugins/mythgame/mythgame/romedit.h
   trunk/mythplugins/mythgame/mythgame/rominfo.cpp
   trunk/mythplugins/mythmusic/mythmusic/globalsettings.cpp
   trunk/mythplugins/mythmusic/mythmusic/globalsettings.h
   trunk/mythplugins/mythphone/mythphone/PhoneSettings.h
   trunk/mythplugins/mythvideo/mythvideo/globalsettings.h
   trunk/mythtv/libs/libmyth/dbsettings.cpp
   trunk/mythtv/libs/libmyth/dbsettings.h
   trunk/mythtv/libs/libmyth/langsettings.cpp
   trunk/mythtv/libs/libmyth/managedlist.h
   trunk/mythtv/libs/libmyth/settings.cpp
   trunk/mythtv/libs/libmyth/settings.h
   trunk/mythtv/libs/libmythtv/channeleditor.cpp
   trunk/mythtv/libs/libmythtv/channeleditor.h
   trunk/mythtv/libs/libmythtv/channelsettings.cpp
   trunk/mythtv/libs/libmythtv/channelsettings.h
   trunk/mythtv/libs/libmythtv/diseqcsettings.cpp
   trunk/mythtv/libs/libmythtv/diseqcsettings.h
   trunk/mythtv/libs/libmythtv/dvbtransporteditor.cpp
   trunk/mythtv/libs/libmythtv/dvbtransporteditor.h
   trunk/mythtv/libs/libmythtv/playgroup.cpp
   trunk/mythtv/libs/libmythtv/playgroup.h
   trunk/mythtv/libs/libmythtv/profilegroup.cpp
   trunk/mythtv/libs/libmythtv/profilegroup.h
   trunk/mythtv/libs/libmythtv/recordingprofile.cpp
   trunk/mythtv/libs/libmythtv/recordingprofile.h
   trunk/mythtv/libs/libmythtv/scanwizard.h
   trunk/mythtv/libs/libmythtv/scanwizardhelpers.cpp
   trunk/mythtv/libs/libmythtv/scanwizardhelpers.h
   trunk/mythtv/libs/libmythtv/scanwizardscanner.cpp
   trunk/mythtv/libs/libmythtv/scheduledrecording.cpp
   trunk/mythtv/libs/libmythtv/scheduledrecording.h
   trunk/mythtv/libs/libmythtv/signalmonitor.h
   trunk/mythtv/libs/libmythtv/sr_items.h
   trunk/mythtv/libs/libmythtv/videosource.cpp
   trunk/mythtv/libs/libmythtv/videosource.h
   trunk/mythtv/libs/libmythui/mythmainwindow.cpp
   trunk/mythtv/programs/mythfrontend/globalsettings.cpp
   trunk/mythtv/programs/mythfrontend/globalsettings.h
   trunk/mythtv/programs/mythtv-setup/backendsettings.h
   trunk/mythtv/programs/mythwelcome/welcomesettings.h

Log:

Refs #2533. Settings inheritence cleanup.

I've talked about this a bit over the last year or so, but I finally had some time to fix it early last week, I found a couple problems and fixed them but it has been fairly trouble free.

The settings code has been violating Qt rules for some time. The two rules it has been violating are:
  no multiple inheritence of QObject
  no virtual inheritence of QObject

The first breaks the Qt signal/slot mechanism because qmake assigns a unique integer to each slot iff there is no multiple or virtual inheritence of QObjects. We've avoided the problems by always placing parents without slots last in the inheritence order and by making all but one of QObject derived parents virtual. When someone accidentally inherits from two QObject derived classes with slots, or tries to use Qt timers the wrong slot will be used on some systems, but not necessarily on the developer's machine, which not only makes MythTV unstable but is very hard to debug.

The virtual inheritence has it's own problems, and is why we needed to initialize all the parents separately in child classes. For example:
{{{
    ConfigurationGroup(true, true, false, false),
    VerticalConfigurationGroup(true, true, false, false),
    TriggeredConfigurationGroup(true, true, false, false)
}}}
is a construct you see a lot of in MythTV settings code. This has also led to some odd constructs for Wizards and TriggeredConfigurationGroup instances. In addition Qt does not generate slots correctly for virtually inherited parents, so any slots in virtually inherited parents can missfire.

To avoid these problems I made the Storage classes not inherit from QObject. Because some of the storage classes need to call Setting methods the Storage classes (except for TransientStorage) take a pointer to their associated Setting in leu of inheritence. Since the Configurable classes need to be able load and save themselves they too get a pointer to their associated Storage class. In fact, I haven't changed the immediate inheritence at all for most classes; so a class such as HostComboBox inherits from ComboBoxSetting and HostDBStorage (this used to be ComboBoxSetting and HostDBSetting) and passes this as the Storage and Setting class resp. 

There were a few exceptions, some classes inherited from three QObject derived classes. Usually these were HorizontalConfigurationGroup/VerticalConfigurationGroup and TriggeredConfigurationGroup OR ListBoxSetting and ConfigurationDialog. For the first case I modified TriggeredConfigurationGroup to treat addChild() instances as if the were inserted into a horizontal or vertical configuration group and treat the addTrigger() instances as if they were inserted into the triggered configuration group, so that the API didn't change except that you only inherit from TriggeredConfigurationGroup and call SetVertical(false) if you want a horizontal layout instead of the default vertical one. The ListBoxSetting and ConfigurationDialog classes were converted to  ConfigurationDialog's with a ListBoxSetting added.

When the settings-revamp is synced to this code it should automagically become much more stable, which is why its tracking ticket is referenced...

It might be possible to get rid of QObject use in the Setting derived classes as well, but this would involve many more changes, the storage classes did not use any QObject features, but only inheritted from Storage in order to access it's members so this change is fairly trivial, it just touches on a lot of code.