@ Head

GO CATS !!!

Queen Protea - pink ice

Here's before and after pictures of pink ice protea:

Echidna photos

late this afternoon I noticed an echidna walking around near one of the wind breaks, so I snapped a few photos. Usually they burrow in when people approach, this  one did but then decided to stick his/her nose out to say hi :)

More photos of him/her on my picassa gallery:
http://picasaweb.google.com.au/Bill.McCarthy.MVP/TheFarm

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"Is" gets a new role in VB 2008

Thanks to Julie's post, I decided to dig deeper into the depths of VB than any sane man should go. While playing with nullable dates in the query, I was wondering why I could get the number of orders with a null ShipDate.

I tried:

Dim query = From order In db.SalesOrderHeaders _
            Where Not order.ShipDate = Nothing

that returned 0.

Then I thought what about Is ?

Dim query = From order In db.SalesOrderHeaders _
            Where Not order.ShipDate Is Nothing

That returns the correct number, which in my modified data is 2.

Now the thing to note here is that ShipDate is a Nullable(of Date), and as such is a value type.  If you try to use the Is operator with a nullable type in VB 2005 you'll get an error telling you can't use Is with value types.  In fact you'll get the same error in VB9 (2008) unless the operand is Nothing, e.g:

Dim dt1 As Date?

Dim dt2 As Date?

Dim result As Boolean = dt1 Is Nothing ' legal

Dim result2 As Boolean = dt1 Is dt2 ' ILLEGAL

So, the new role for Is is when comparing a nullable type to the Nothing constant.

 And likewise you can use IsNot with Nothing on nullable types too,

Moved my photos

As I uploaded a couple more photos to my flickr account, I got a warning that I had exceeded the 200 photo limit.  After looking for alternatives, such as My Spaces etc, I settled on Google's Picasa.  The software is easy to use (although it lacks tagging it does albums well.  So my photo gallery is now at

http://picasaweb.google.com/Bill.McCarthy.MVP

C# defies logic

C# has some interesting rules for operators on nullable types. Given:

int? x ;
int? y ;

Laws of transitivity tells us that if x is equal to y, (x == y), then x<= y would be true too. Well not in C#.

With this function:

static void test(int? arg1, int? arg2)
{
    Console.WriteLine("arg1 == arg2 returns {0}", (arg1 == arg2));
    Console.WriteLine("arg1 <= arg2 returns {0}", (arg1 <= arg2));
}

The output in some cases will be:

arg1 == arg2 returns True
arg1 <= arg2 returns False

Sad to see C# break basic laws of logic and mathematics like this. :(  

Thankfully VB doesn't make this mistake :)

Spring is here :)

Spring is here, the weather is lovely and some of the fruit trees are in full blossom  :)

New twin head lawn mower for Spring

It's Spring here, and I got me a new automatic twin head lawn mower:

Another Vb'er gets bit by Option Strict