Explain object use; using object before it's constructed 2

[cjburkha]

I think I have a fair grip on OOP, but this part of VB.NET has me a bit confused:

sub Page_Load(sender As Object, e As EventArgs)
dim maxDaysNewMonth as integer =  datetime.DaysInMonth(1996, 2)
response.write(maxDaysNewMonth)
end sub

What confuses me is the datetime method call. My can I use a method of this class, when I havn't created the object yet? Is this an object that is made available to me my the .NET framework somehow? The page somehow makes this object availabe to me, just like the response object? I looked in MSDN, and they don't even call this a class, but rather a structure, but it still has methods.

Does anyone have any insight into this? Any pointers? Links?

I mean, I wouldn't do this:

dim intStringLength = String("Steve").Length

 

[JohnYingling]

It has been declared as a Shared (VB) or Static (C#) method which therefore has no instance data.

http://www.VBCompare.com

Compare Code

 

[chiph]

When you look in the online help, if you see the yellow "S" beside a method or property, that indicates that it's a Shared or Static member, and that you call it by using the class name, and not an instance of the class.

People usually write them as a convenience to the class' user -- they're usually methods that perform some utility function that don't affect any stored instance data in the class. XmlConvert is a good example.

When writing your own classes, try not to use them if you can avoid it. A class with all-static member is little better than a kitchen sink.

Chip H.


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[cjburkha]

Thanks guys, your answers explained it, and led me to this link:

http://www.developerfusion.com/show/1047/5/

This is pretty handy stuff, but I can see how you would only want to use it in the right circumstance.

CJB