CODEWITHSUNDEEP
vb.netdesign-patterns
w0051977
w0051977

Reputation: 15807

Using objects in shared functions

Please take a look at the code below:

    Imports System.Data.SqlClient
Public Class Person
    Private id As String
    Private name As String

    Public Function check(ByVal personid As String) As Boolean
        'Do some checks on the person to see if it is ready for deletion
    End Function

    Public Shared Sub Delete()
        Dim v As New Vehicle
        Dim p As New Person
    End Sub
End Class

Public Class Vehicle
    Private vrm As String

    Public Function check(ByVal vehicleid As String) As Boolean
        'Do some checks on the vehicle to see if it is ready for deletion
    End Function

    Private Shared Sub Delete()
        Dim p As New Person
        Dim v As New Vehicle
        Dim objCommand As SqlCommand
        Dim objCon As SqlConnection
        Dim objDR As SqlDataReader
        Try
            Dim _ConString As String = "Data Source=IANSCOMPUTER;Initial Catalog=Test;Integrated Security=True;MultipleActiveResultSets=true"
            objCon = New SqlConnection(_ConString)
            objCommand = New SqlCommand("SELECT * FROM Person were startdate < dateadd(year,-6," & Now & ")")
            objDR = objCommand.ExecuteReader
            Do While objDR.Read
                If p.check(objDR("id")) And v.check(objDR("vehicleid")) Then
                    'Execute delete statement, which deletes the person and vehicle
                End If
            Loop
            objDR.Close()
            objCommand.Connection = objCon
            objCon.Open()
            objCommand.ExecuteNonQuery()
        Catch ex As Exception
            Throw
        Finally

        End Try
    End Sub

End Class

Notice that the shared function (Person.Delete) contains references to Person and Vehicle and uses instance variables in Person and Vehicle. Basically a check needs to be done on the Person and vehicle before the person and vehicle can be deleted.

Is it poor practice to reference Person and Vehicle from the Shared function? Is it poor practice to use instance variables in the Delete function. The Delete function will delete thousands of persons and vehicles daily.

Upvotes: 0

Views: 314

Answers (1)

mr_plum
mr_plum

Reputation: 2437

It's not necessarily a bad practice to make them shared, but if they are shared its a good practice to refactor them into their own classes. Shared instantly makes then global functions that, in my mind, should not contaminate the class signature.

So this would be better practice in my estimation:

Public Class Person
    Private id As String
    Private name As String
End Class

Public Class Vehicle
    Private vrm As String
End Class

Public Class PersonVanisher
    Public Shared Sub Delete()
        Dim v As New Vehicle
        Dim p As New Person
        ...
    End Sub

    Public Shared Function Check(personId As String) As Boolean
        ...
    End Function
End Class

Public Class VehicleCrusher
    Private Shared Sub Delete()
        Dim p As New Person
        Dim v As New Vehicle
        ...
    End Sub

    Public Shared Function Check(vehicleId As String) As Boolean
        ...
    End Function
End Class

People get into philosophical debates about this, but if it were my code I would not make anything shared. I would prefer to "New up" a VehicleCrusher when I need it and let .NET dispose everything as soon as I'm done.

Upvotes: 1

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