Advanced usage of the ?? operator

P.J. van de Sande from the (Dutch) weblog Born 2 Code .NET has two posts about the in .NET 2.0 new ?? operator. In the first post he explains what it does and why he likes it. After some comments, he decided to write another post about it, trying to explain even further why he likes it so much. But now he pulls some code from his sleeve I really had to take a good look at.



public Brush BackgroundBrush


{


  get


  {


    return _backgroundBrush ??


    (


        _backgroundBrush = GetBackgroundBrushDefault()


    );


  }


}


You have to know how this is evaluated to understand it. Before it returns anything, it first evaluates the ?? operator, which is probably understood much better by the following code block.



public Brush BackgroundBrush


{


  get


  {


    if (_backgroundBrush == null)


    {


      _backgroundBrush = GetBackgroundBrushDefault();


    }


 


    return _backgroundBrush;


  }


}


But still, it’s some lovely code. You decide for yourself if you want to see code like that in your project. Perhaps Jan Schreuder would be more happy to see code like this instead of the code in his latest post! 😉

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6 Responses

  1. Ramon Smits says:

    This makes use of the construction that each statement has a return value.

    int a,b,c;

    a=b=c=6;

    Now all three value types will be 6 🙂

    Just excellent c behaviour that we have inherited.

  2. Ramon Smits says:

    Or like copying stream data into another.

    static void Copy(Stream source, Stream destination)
    {
    ■■■const long Size = 1024;
    ■■■byte[] buffer = new byte[Size];
    ■■■long readBytes;

    ■■■while(0<(readBytes=source.Read(buffer,0,readBytes))
    ■■■{
    ■■■■■■destination.Write(buffer,0,readBytes);
    ■■■}
    }

    ps. This code could contain errors as I just typed it in by hand.

  3. Paul Gielens says:

    With a background in C++ ?? makes perfect sense.

  4. eeeeeeeeeeeeeeeeuuch !!!

    What total retard came up with the idea that it was necessary to shorten 6 characters (==null) to 2 characters(??). And what’s even worse, it looks like the statement doesn’t go between the normal {} but between ().

    I’m boycotting this thing for life.

  5. Remco, thank you for your objective comment! 😀

    I’ll go contact Blizzard if they can add this most beautifull ?? operator into the World of Warcraft scripting language! That’ll be the way to get you over the edge! 😀

  6. JanellHess22 says:

    This is good that we are able to take the loans moreover, that opens completely new possibilities.

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