Spot the bug #2

Code:

// Add the arguments for all switchable files
foreach ( SwitchableFile switchableFile in Settings.SwitchableFiles.Values )
{
    optionSet.Add( string.Format( "{0}", switchableFile.WhetherToSwitchArg ),
        string.Format( "Switch {0}", switchableFile.NormalFile ),
        argExistence => Settings.SwitchFile[ switchableFile.Name ] = ( argExistence != null ) );
    
    ...
}

Only C# gurus will get this one.

 Hint 1

Arguments created for all switchable files actually affected the last SwitchableFile in Settings.SwitchableFiles.Values.

 Hint 2

Think about the rules for captured variables in lambda expressions.

 answer

Code:

// Add the arguments for all switchable files
foreach ( SwitchableFile switchableFile in Settings.SwitchableFiles.Values )
{
    [color="red"]// Cannot use switchableFile.Name in the lambdas because the switchableFile
    // variable has only one instance - so the switch and noswitch arguments
    // for all switchables would actually be bound to the last switchable.
    string switchableName = switchableFile.Name;[/color]

    optionSet.Add( string.Format( "{0}", switchableFile.WhetherToSwitchArg ),
        string.Format( "Switch {0}", switchableFile.NormalFile ),
        argExistence => Settings.SwitchFile[ [color=red]switchableName[/color] ] = ( argExistence != null ) );
    
    ...
}

I need to read up on my C++ again, cuz thats was like a tongue twister in the brain.