[Developers] Storing user-specific settings

[Bert Bril]

Hi all,


In many places there are things that are specific per user. Colors,
default values, and so forth.

For these defaults per user, there is the 'Settings' object
(Basic/settings.h). It is basically an IOPar which is automatically
loaded and stored in the right place with the right file name.

For OpendTect-base things there is the instance 'Settings::common()',
which for example has:
SEG-Y.Examine.Number of traces: 1500
The value is read when the SEG-Y 'wizard' starts:

    int nrex = 100;
    Settings::common().get( sKeySettNrTrcExamine, nrex );

When the user checks the 'Save as default' box the value will be saved:

    const int nrex = nrTrcExamine();
    Settings::common().set( sKeySettNrTrcExamine, nrex );
    Settings::common().write();

The Settings::common() instance is meant for OpendTect-base. If you want
to store/retrieve deaults for your specific plugin, all you have to do
is ask for an instance. If there was already a file, it will be read.
Otherwise, a new one is created. Thus you'd have:

    Setings::fetch( "MeMySelfAndI" ).get( "The Value", val );

and

    Settings& mysetts = Setings::fetch( "MeMySelfAndI" );
    mysetts.set( "The Value", val );
    mysetts.write();

A nice example is when you want to display a certain message once ever
per user. Like what the actual meaning of something is. Displaying it
again would be annoying. That could be done with:

    static const char* skey = "Inversion.Complicated Message Done";
    Settings& setts = Settings::fetch( "FooBarCompany" );
    if ( !setts.isTrue(skey) )
    {
        setts.setYN( skey, true );
        setts.write();
        if ( !uiMSG().askGoOn( "This is awfully complicated!"
                               "\n\nDo you want to continue?" ) )
            return false;
    }




-- Bert

-- 
-- Bert Bril / OpendTect developer at dGB
-- mailto:Bert.Bril at opendtect.org , http://opendtect.org