[2005] Question about writing a class

[drpcken]

I'm working on a class using a tutorial and I'm wondering about something I'm seeing.

<vbcode>
<System.ComponentModel.DataObject()> _
Public Class ProductsBLL

Private _productsAdapter As ProductsTableAdapter = Nothing
Protected ReadOnly Property Adapter() As ProductsTableAdapter
Get
If _productsAdapter Is Nothing Then
_productsAdapter = New ProductsTableAdapter()
End If

Return _productsAdapter
End Get
End Property

End Class</vbcode>

Why all the underscores (_) ??
In the _productsAdapter declaration, why the underscore?

I'm confused.

Thanks!

[seidel1]

Its just a good way to declare variables, easy to see and used as a standard in many shops

[drpcken]

wow i've never seen it. So do I call my variables like that too?

thanks for the quick response!

[Jumpercables]

The _ usually indicates member vairables lots of microsoft people use the mixture of _ and m_variable.

[mendhak]

The first underscore is a line continuation.

<System.ComponentModel.DataObject()> _
Public Class ProductsBLL

means:

<System.ComponentModel.DataObject()> Public Class ProductsBLL

Using underscores in variable names is an old way of indicating private variables in a class.

[drpcken]

The first underscore is a line continuation.

<System.ComponentModel.DataObject()> _
Public Class ProductsBLL

means:

<System.ComponentModel.DataObject()> Public Class ProductsBLL

Using underscores in variable names is an old way of indicating private variables in a class.

Why have the namespace before the declaration of the class? I've never seen that before (before and after the line continuity)

[mendhak]

You're talking about the part in <> right? That's not a namespace, that's an attribute. It is a way of tagging up the function or class. This specific one tags the class as a 'dataobject'.

This means that an object of this class type can be bound to.

[drpcken]

ohhh i see... kinda

So your tagging the DataObject attribute to the class... i got that

But I'm not quite sure what you mean when you say "This means that an object of this class type can be bound to."

Here's a better example perhaps:

<System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Select, True)> _
    Public Function GetProducts() As Northwind.ProductsDataTable
        Return Adapter.GetProducts()
    End Function

[mendhak]

For a DataObject class, the DataObjectMethodAttribute attribute would specify what it does, and whether it's the default method for that dataobject class.

About what I meant. You know about the dataset class. The dataset class can be bound to. The datagrid, when it binds to a dataset, will expect that the dataset knows what information it has, how to retrieve, update, manipulate it.

Similarly, there's your DataObject attributed-class. You're essentially creating a custom dataset specific to your application.

[drpcken]

Excellent! That clears things up a bit!